Which of the following modifiers can be applied to an abstract method?
D.
An abstract method cannot include the final or private method.
If a class contained either of these modifiers, then no concrete subclass would ever be able to override them with an implementation.
Options A and B are incorrect.
Option C is also incorrect because the default keyword applies to concrete interface methods, not abstract methods.
Option D is correct.
The protected, package-private, and public access modifiers can each be applied to abstract methods.