Final answer:
Interfaces, abstract classes, and enums cannot be instantiated, as interfaces and abstract classes are meant to be implemented or extended by other classes, and enums define a fixed set of constants. Only final classes can be instantiated but cannot be subclassed.
Step-by-step explanation:
In the context of programming, certain reference types cannot be directly instantiated, that is, you cannot use the new keyword to create an instance of them. The reference types from the options provided that cannot be instantiated are:
- Interface
- Abstract class
- Enum
An interface defines a contract that classes can implement but by itself, it does not contain implementation details, and thus cannot be instantiated. Similarly, an abstract class is a class that is declared abstract—it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed. In the case of an enum, it is a special type of class that defines a collection of constants, and you cannot create new instances of an enum type. On the other hand, a final class is a class that can be instantiated but cannot be subclassed. Therefore, you can create instances of a final class, making it the only option from the list that can be instantiated.