Consider the classes below, declared in the same file:

```
class A
{
int a;
public A()
{
a = 7;
}
}

class B extends A
{
int b;
public B()
{
b = 8;
}
}
```

Which of the statements below is false?
a. Both variables a and b are instance variables.
b. After the constructor for class B executes, the variable a will have the value 7.
c. After the constructor for class B executes, the variable b will have the value 8.
d. A reference of type A can be treated as a reference of type B.

d. A reference of type A can be treated as a reference of type B.