Answer:A) O(1)
Explanation:Double linked chain is the type of the data structures that are linked with each other .There are the components that contain the set of records in a queue manner and forms the links which are referred as the nodes.
The operation performed by the dequeue operator is of  eliminating the element which is at the front. So, when the operation of the dequeue operation gets invoked then the functioning of initializing of new dequeue and removing the front value by O(1) method.
