According to docs
A class type should be declared abstract only if the intent is that subclasses
can be created to complete the implementation. If the intent is simply to prevent
instantiation of a class, the proper way to express this is to declare a
constructor of no arguments, make it private, never invoke it, and declare no
other constructors.
Abstract class can have not abstract methods but it must have a valid use case(like calling super from subclass). You cannot instantiate(create objects of abstract class).
So either remove abstract keyword or create another class that extends your abstract class.
Ans just for the record when an abstract class implements an interface you need not implement the interface methods in abstract class(though you can if your design dictates so). But in case you don't implement interface methods in the abstract class implementing it you need to implement the same in first concrete subclass of your abstract class. Also if you do implement you interface methods in abstract class then no need to implement them again in the concrete subclass of the abstract class. You can always override it though.
C, which is the normal behaviour for abstract classes. (Note that you'd need to declare astatusvariable inCforCto even compile, of course.)