A stack is implemented as a singly linked list. Which operation is the most expensive in terms of time complexity?PushPopPeekNone of the above

In a stack implemented as a singly linked list, the most expensive operation in terms of time complexity is None of the above. This is because all three operations - Push, Pop, and Peek - can be performed in constant time O(1).

Here's why:

1. Push: This operation involves adding an element at the head of the linked list. This can be done in constant time as it does not depend on the size of the list.

2. Pop: This operation involves removing an element from the head of the linked list. Similar to the Push operation, this can also be done in constant time.

3. Peek: This operation involves returning the value of the head of the linked list without removing it. Again, this operation can be performed in constant time.

So, none of the operations mentioned above have a time complexity greater than O(1).