Which statement about abstract classes is accurate?

• A. An abstract class can be instantiated
• B. All methods in an abstract class are required to be abstract
• C. Abstract classes can contain both abstract and non-abstract methods
• D. Abstract classes cannot have subclasses

Answer: (C)

An abstract class serves as a blueprint for other classes and is fundamental in object-oriented programming. The correct statement indicates that abstract classes can contain both abstract methods, which are declared without an implementation, and non-abstract methods, which have a defined implementation. This flexibility allows for a combination of shared behaviors (through non-abstract methods that can be reused) while still providing the structure needed for subclasses to implement specific behaviors (through abstract methods that the subclasses must define).

For example, an abstract class may define a method that all subclasses can use, providing general functionality while also declaring other methods that must be specifically implemented by those subclasses. This design principle promotes code reuse and abstraction, enabling developers to focus on what actions an object can perform without getting into the details of how those actions are performed.

The other statements do not accurately represent the principles of abstract classes. For instance, an abstract class cannot be instantiated directly—this reinforces the concept that it is incomplete without the specific implementations provided by subclasses. Additionally, it is not required for all methods within an abstract class to be abstract; it can include both types of methods. Abstract classes can and typically do have subclasses that provide specific implementations for abstract methods, thereby extending the functionality outlined in the abstract class.