Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct?1. A a = new A();2. A a = new B();3. B b = new A();4. B b = new B();

A).  1 and 2

B).  3 and 4

C).  3 and 4

D).  1 and 3

E).  2 and 3

 2 and 4

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