Consider the AddFirst Method of the LinkedList Class in Chapter

Consider the addFirst method of the LinkedList class in Chapter 16: /**
Adds an element to the front of the linked list.
@param element the element to add
*/
Public void addFirst(Object element)
{
Node newNode = new Node() ;
NewNode.data = element;
NewNode.next = first;
First = newNode;
}
Three implementations have been proposed to make the addFirst method thread safe where listLock is a variable of type ReentrantLock. Which of them will work?
I.
ListLock.lock() ;
Try
{
Node newNode = new Node() ;
NewNode.data = element;
NewNode.next = first;
}
Finally
{
ListLock.unlock() ;
}
First = newNode;
II.
Node newNode = new Node() ;
NewNode.data = element;
NewNode.next = first;
ListLock.lock() ;
Try
{
First = newNode;
}
Finally
{
ListLock.unlock() ;
}
III.
ListLock.lock() ;
Try
{
Node newNode = new Node() ;
NewNode.data = element;
NewNode.next = first;
First = newNode;
}
Finally
{
ListLock.unlock() ;
}

A) None of them
B) III only
C) II and III only
D) All of them