To declare a class in most programming languages such as Java or C++, the keyword "class" is required.

Let's go through each option to understand why it is correct or incorrect:

Option A) public - The "public" keyword is used to specify the visibility level of class members (variables and methods), but it is not required to declare a class itself.

Option B) private - The "private" keyword is also used to specify the visibility level of class members, but it is not required to declare a class itself.

Option C) class - This option is correct because the "class" keyword is indeed required to declare a class. It is used to define a new class and its associated properties and methods.

Option D) All of the above - This option is incorrect because only Option C (class) is required to declare a class. Options A and B are used to specify the visibility level of class members, but they are not necessary for declaring a class itself.

Therefore, the correct answer is C) class.

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• Wrong explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) The program has a compilation error because TempClass does not have a default constructor.

This option is incorrect because the TempClass class does not require a default constructor. In the code provided, a parameterized constructor is defined in the TempClass class, which takes an int argument. Therefore, a default constructor is not needed.

Option B) The program has a compilation error because TempClass does not have a constructor with an int argument.

This option is correct because the code provided attempts to create an instance of the TempClass class with an int argument (2). However, the TempClass class only defines a parameterized constructor, which does not match the provided argument. As a result, there is a compilation error because there is no constructor in the TempClass class that accepts an int argument.

Option C) The program compiles fine, but it does not run because class C is not public.

This option is incorrect because the C class does not have any impact on the compilation or execution of the code. It is not being used or referenced in any way, so the accessibility of the C class does not affect the program's behavior.

Option D) The program compiles and runs fine.

This option is incorrect because there is a compilation error in the code. As explained in option B, the TempClass class does not have a constructor that accepts an int argument, and the code attempts to create an instance of TempClass with an int argument (2). Therefore, the program will not compile successfully.

The correct answer is B. The program has a compilation error because TempClass does not have a constructor with an int argument.

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• Wrong explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) true, 1, Null - This option is incorrect because the default value for a boolean type is false, not true. Also, the default value for a numeric type is 0, not 1. Lastly, the default value for an object type is null, not Null.

Option B) false, 0, null - This option is correct. The default value for a boolean type is false, the default value for a numeric type is 0, and the default value for an object type is null.

Option C) true, 0, null - This option is incorrect because the default value for a boolean type is false, not true. Also, the default value for a numeric type is 0, not 1. Lastly, the default value for an object type is null, not Null.

Option D) true, 1, null - This option is incorrect because the default value for a boolean type is false, not true. Also, the default value for a numeric type is 0, not 1. Lastly, the default value for an object type is null, not null.

The correct answer is B. This option is correct because the default value for a boolean type is false, the default value for a numeric type is 0, and the default value for an object type is null.

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• Wrong explanation

To answer this question, you need to understand the concept of class variables.

Option A) Public variables - This option is incorrect because public variables can be accessed and modified by any instance of a class, but they are not necessarily shared by every instance of the class.

Option B) Private variables - This option is incorrect because private variables are only accessible within the class itself and cannot be accessed or modified by instances of the class.

Option C) Instance variables - This option is incorrect because instance variables are unique to each instance of a class. Each instance has its own copy of the instance variables.

Option D) Class variables - This option is correct because class variables are shared by every instance of a class. They are declared at the class level and are accessed using the class name rather than an instance of the class.

The correct answer is D) class variables. This option is correct because class variables are shared by every instance of a class.

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• Wrong explanation

To answer this question, we need to understand what group functions are in the context of databases.

Group functions, also known as aggregate functions, are functions that perform calculations on a set of values and return a single value. These functions are commonly used in SQL queries to summarize data. Some examples of group functions include AVG(), SUM(), and MAX().

Let's go through each option to determine which one is not a group function:

Option A) avg( ) - This option is a group function. The AVG() function calculates the average value of a set of values.

Option B) sqrt( ) - This option is not a group function. The SQRT() function calculates the square root of a single value, not a set of values. Therefore, this is the correct answer.

Option C) sum() - This option is a group function. The SUM() function calculates the sum of a set of values.

Option D) max() - This option is a group function. The MAX() function returns the maximum value from a set of values.

Therefore, the correct answer is B) sqrt( ) because it is not a group function.

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• Wrong explanation