Consider an implementation of unsorted single linked list. Suppose it has its representation with a head and a tail pointer $($i$.$e$.$ pointers to the first and last nodes of the linked list$).$ Given the representation, which of the following operation can not be implemented in O$(1)$ time $?$

Select one:

a$.$ Insertion at the end of the linked list.

b$.$ Deletion of the last node of the linked list.

c$.$ Deletion of the front node of the linked list.

d$.$ Insertion at the front of the linked list.