Correct Answer:
C. c) Single ended queue
Explanation:
Why "Single-ended queue" is not a type of queue?
A queue is inherently a double-ended data structure.
It has two primary operations: enqueue (adding to the rear) and dequeue (removing from the front).
The term "single-ended queue" is a contradiction.
If it were single-ended, it would essentially be a stack, not a queue.
Therefore, among the given options, single-ended queue is not a valid type of queue.
The other options are valid queue types:
Priority queue: Elements have priorities, and the highest priority element is dequeued first.
Circular queue: The rear and front pointers wrap around to the beginning of the array when they reach the end.
Ordinary queue: The standard queue implementation with a front and rear pointer.