What kind of linked list is best to answer question like “What is the item at position n?” a) Singly linked list b) Doubly linked list c) Circular linked list d) Array implementation of linked list

Let P be a single linked list.Let Q be a pointer to an intermediate node 'X' in the list.What is the worst case time complexity of best known algorithm to delete the node 'X ' from the list

What would be the asymptotic time complexity to add a node at the end of singly linked list, if the pointer is initially pointing to the head of the list? O(n) O(1) θ(n2) θ(n)