Enthuware

Type A implements method process().
Both interface and abstract class can implement methods. Interface can do it by default method. So, I think, that correct answer is "A may be an abstract class or an interface.". Why not?

Interface cannot implement anything. Remember that this exam is for Java 7.

HTH,
Paul.

A must implement an interface. - isn't it true? Type A implements method process(). Or it can be impemented from another abstract class?

Implementing a method doesn't mean implementing an interface. It just means that the class has a non-abstract method. In other words, the class has proper working code for that method. Whether that method is a part of some other interface or abstract class is irrelevant.

HTH,
Paul.

Thanks, Paul!