The following question refers to the attached code:

public class A extends B { public A () { ... } public A(int a) { super(a); ... } public A(String a, int b) { super(a); ... } }

Mark all the constructors which must be in the class B such that the excevation works.

a public B(int a) { }

b public B(String a) { }

c public B() { }

d public B(A a) { }

e public B(String a, int b) { }