A Stack Based on a Linked List Is Based on the Following

A stack based on a linked list is based on the following code
Class Node{
String element;
Node next;
Node(String el,Node n) {
Element = el;
Next = n;
}
}
Node top = null;
The code for implementing the String peek() operation is

A) String temp = top.element;
If (temp != null) return temp;
Else
Throw new RuntimeException("Empty Stack") ;
B) if (top != null.
Return top.element;
Else return top.next;
C) if (top != null.
Return top.element
Else
Throw new RuntimeException("Empty Stack".;
D) if (top != null.
Return top;