Stack with nodes question

I recently took a test for my class and got the test back and got this part of the test all wrong

Code:

public class Stack<E> { static class SNode<T> { T data; SNode<T> next; SNode(T d, SNode<T n> { data = d; next = b; } SNode(){this(null,null)} } private SNode<E> top; //pointer to top of stack private int size; void push(E elt){ /*this needs to be defined */} }

a)
SNode<E> tmp = new SNode<E>();
tmp.next = top;
top = tmp;
top.data = elt;
size++;

b)
SNode<E> tmp = new SNode<E>();
top = tmp;
tmp.next = top;
tmp.data = elt;
size++;

c)
top = new SNode<E>(elt,top);
size++

The question is whether those are the correct body for the push method. Those are the ones I got wrong so if anyone can help id appriciate it.
If you can give me step by step instructions on what points to what and how that means its a valid push method id appriciate it.

Oh and the answers are yes, no, and yes.