Java Programming - Language Fundamentals - Discussion
Option A is correct. A public access modifier is acceptable. The method prototypes in an interface are all abstract by virtue of their declaration, and should not be declared abstract.
Option B is wrong. The final modifier means that this method cannot be constructed in a subclass. A final method cannot be abstract.
Option C is wrong. static is concerned with the class and not an instance.
Option D is wrong. protected is not permitted when declaring a method of an interface. See information below.
Member declarations in an interface disallow the use of some declaration modifiers; you cannot use transient, volatile, or synchronized in a member declaration in an interface. Also, you may not use the private and protected specifiers when declaring members of an interface.
Interface may contain declaration of method but, not its implementation. That method have to be necessarily implemented in subclass.
b & c can't be because of final & static keyword respectively as they use in case of class but in interface.
Could you please elaborate your answer?