The following code for two classes in the same package does not compile as expected. Why not?

Select the one correct statement.

public class B1 { private int b; private int c; /** * Constructors for objects of class B1 */ public B1(int b, int c) { this.b = b; } public B1() { } } public class B2 extends B1 { private int c; /** * Constructors for objects of class B2 */ public B2(int a, int b, int c) { super(a); this.c = 0; } public B2() { } } 

Select one or more:

The argument name in the two-argument constructor of class B1 is the same as the instance variable (b) in class B1.

The 3-argument constructor of class B2 doesn't make use of the argument c to initialise the instance variable c.

There is no single argument constructor in class B1.

The instance variable c in class B1 has not been explicitly initialised in the constructor.

The zero-argument constructor in class B2 does not explicitly invoke the zero-argument constructor in class B1.