A queue is implemented using a non$-$circular singly linked list. The queue has a head pointer and a tail pointer, as shown in the figure. Let n denote the number of nodes in the queue. Let 'enqueue' be implemented by inserting a new node at the head, and 'dequeue' be implemented by deletion of a node from the tail.circular$-$linked$-$lis

Which one of the following is the time complexity of the most time$-$efficient implementation of 'enqueue' and 'dequeue, respectively, for this data structure?

Your answer:

Theta $($n$),$Theta $($n$)$

Theta $($n$),$Theta $(1)$

Theta $(1),$Theta $($n$)$

Theta $(1),$Theta $(1)$

head tail