Ans: D) O(1)
Stack is the data structure with LIFO(Last In First Out) property.
In Linked-List based Implementation of stack.
- push/ insert operation = create a data node and insert it at the head of the linked list and update the pointer.
- pop/ remove operation = delete the node from the head of the list and update the "head" pointer.
Both operation can be done in O(1) operation.