In an object oriented language such as Java or C Sharp, if you do not want your class to be inherited by any other class, what should you do when declaring it?

Introduction / Context:
Sometimes you design a class that should not be used as a base for further inheritance. For example, you may want to prevent changes to security related behaviour or to keep the class simple and closed for extension. Most object oriented languages provide a way to mark such classes so that the compiler prevents inheritance. This question tests whether you know which modifier to use in common languages such as Java and C Sharp.

Given Data / Assumptions:

• We are working with mainstream object oriented languages that support access modifiers and inheritance controls.
• The goal is to prevent any other class from inheriting from the given class.
• We want a compile time restriction rather than a runtime check.

Concept / Approach:
In Java, the final keyword can be applied to classes. A final class cannot be subclassed, which means no other class can extend it. In C Sharp, a similar effect is achieved by marking the class as sealed. Both modifiers instruct the compiler to reject any attempt to derive from the class. This mechanism is commonly used for utility classes and for classes where the author wants to guarantee behaviour is not changed through inheritance.

Step-by-Step Solution:
Step 1: Identify that the requirement is to block inheritance of a class.Step 2: Recall that Java uses final for this purpose, while C Sharp uses sealed.Step 3: Option A explicitly mentions declaring the class as final in Java or sealed in C Sharp to prevent extension.Step 4: Option B suggests static, which controls member access and instantiation, not inheritance.Step 5: Options C and D misuse private and abstract, which do not forbid inheritance in the required way, so option A is correct.

Verification / Alternative check:
If you declare a class in Java as final class Utility { }, and then try to write class MyUtility extends Utility { }, the compiler will emit an error stating that you cannot subclass a final class. Similarly, in C Sharp, class Utility sealed { } prevents any further inheritance. These simple experiments confirm that final or sealed is the proper way to enforce the restriction.

Why Other Options Are Wrong:
Option B, static, is used for members or nested classes that belong to the type rather than instances. It does not prevent or enforce inheritance on its own. Option C, private, is an access modifier for members and nested types, not a mechanism to freeze inheritance for top level classes. Option D, abstract, does the opposite of what is required; an abstract class is intended to be subclassed and may even require it because it cannot be instantiated directly.

Common Pitfalls:
Some developers try to prevent inheritance by making constructors private, which can be bypassed with nested or factory classes and does not always express intent clearly. Others mark classes as final or sealed too aggressively, limiting flexibility for future changes. When answering exam questions, keep the focus on the standard language feature: use final in Java and sealed in C Sharp to ensure that a class cannot be inherited.

Final Answer:
Declare the class as final in Java or sealed in C Sharp so that no other class can extend or derive from it.