Which of the following linked list will give O 1 complexity?

The concatenation of two lists is to be performed in O(1) time. Which of the following implementations of a list should be used?
(A) singly linked list
(B) doubly linked list
(C) circular doubly linked list
(D) array implementation of lists

Answer: (C)
Explanation: Singly linked list cannot be answer because we cannot find last element of a singly linked list in O(1) time.

Doubly linked list cannot also not be answer because of the same reason as singly linked list.
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