To answer this question, we need to understand the concept of data hiding in the context of database management.

Option A) Conceptual level data hiding - This option is incorrect. Conceptual level data hiding refers to hiding the internal details and complexities of a database from the end-users. It is not directly related to hiding specific salary details from employees.

Option B) Physical level data hiding - This option is incorrect. Physical level data hiding refers to hiding the physical storage details and implementation specifics of a database from the end-users. It is also not directly related to hiding specific salary details.

Option C) External level data hiding - This option is correct. External level data hiding refers to hiding specific data elements or attributes from certain users or user groups. In this case, the manager's salary details are hidden from the employee, which is an example of external level data hiding.

Option D) All of these - This option is incorrect. While it is true that data hiding can occur at multiple levels (conceptual, physical, and external), the given scenario specifically relates to external level data hiding.

Option E) None of these - This option is incorrect. As explained above, the correct answer is Option C, which represents external level data hiding.

Therefore, the correct answer is C) External level data hiding.

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To answer this question, you need to understand what a schema is in the context of databases.

A schema is a blueprint or structure that describes how data is organized in a database. It specifies the data elements, the relationships between these elements, and the organization of records and files.

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

Option A) Data elements - This option is correct because a schema describes the data elements present in a database.

Option B) Records & files - This option is correct because a schema describes the organization of records and files in a database.

Option C) Record relationships - This option is correct because a schema describes the relationships between records in a database.

Option D) All of these - This option is correct because a schema describes all of the above-mentioned aspects: data elements, records and files, and record relationships.

Option E) None of these - This option is incorrect because a schema does describe data elements, records and files, and record relationships.

The correct answer is D) All of these. This option is correct because a schema describes data elements, records and files, and record relationships in a database.

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To answer this question, you need to understand the concept of a Database Management System (DBMS) and its compatibility with different operating systems.

Option A) Scalable - This option refers to the ability of a system to handle an increasing workload or to be easily expanded. While scalability is an important characteristic of a DBMS, it is not directly related to its compatibility with different operating systems.

Option B) Robust - This option refers to the ability of a system to handle errors and exceptions gracefully. While robustness is an important characteristic of a DBMS, it is not directly related to its compatibility with different operating systems.

Option C) Platform independent - This option is correct because a DBMS that runs on many different operating systems is said to be platform independent. This means that the DBMS can be installed and run on various operating systems without requiring significant modifications or adaptations.

Option D) Distributed - This option refers to a DBMS architecture where data is stored and processed across multiple nodes in a network. While a distributed DBMS can also run on different operating systems, it specifically refers to the distribution of data and processing, which is not the focus of the given question.

The correct answer is C) Platform independent. This option is correct because a DBMS that runs on many different operating systems is considered platform independent.

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