Which three are valid?

Given:

11. class ClassA {}
12. class ClassB extends ClassA {}
13. class ClassC extends ClassA {} and:
21. ClassA p0 = new ClassA();

22. ClassB p1 = new ClassB();
23. ClassC p2 = new ClassC();
24. ClassA p3 = new ClassB();
25. ClassA p4 = new ClassC();

Which three are valid? (Choose three.)

A.
p0 = p1;

B.
p1 = p2;

C.
p2 = p4;

D.
p2 = (ClassC)p1;

E.
p1 = (ClassB)p3;

F.
p2 = (ClassC)p4;