Consider the abstract class below:
Public abstract class Foo
{
Private int a;
Public int b;
Public Foo(int aVal,int bVal)
{
A = aVal;
B = bVal;
}
Public abstract int calculate();
}
Any concrete subclass that extends class Foo:
A) Must implement a method called calculate.
B) Will not be able to access the instance variable a.
C) Will not be able to instantiate an object of class Foo.
D) All of the above.

Question

Quizplus · Accepted Answer

A) Any concrete subclass that extends Foo must provide an implementation for the abstract method calculate. 
B) Since the variable a is private, it cannot be accessed by the subclasses. 
C) Since Foo is an abstract class, it cannot be instantiated. Thus, all the options are correct.

Consider the Abstract Class Below