To solve this question, the user must understand the concept of the sealed keyword in object-oriented programming languages.
Explanation:
The sealed keyword is used to restrict inheritance in object-oriented programming. When a class is declared with the sealed keyword, it means that no other class can inherit from it. In other words, a sealed class cannot be used as a base class for another class.
Now, let's go through each option and explain why it is right or wrong:
A. True: This option is correct. When a class is declared with the sealed keyword, it cannot be used as a base class. Other classes cannot inherit from a sealed class.
B. False: This option is incorrect. Classes declared with the sealed keyword cannot be used as a base class, so the statement is true.
The Answer is: A