A queue is implemented using an array such that ENQUEUE and DEQUEUE operations are performed efficiently. Which one of the following statements is **CORRECT** ($n$ refers to the number of items in the queue)?

A queue can be efficiently implemented using a circular array with two pointers, front and rear.

• ENQUEUE operation: Increments the rear pointer using modulo arithmetic (rear = (rear + 1) % capacity) and inserts the element at array[rear]. This takes $O(1)$ time.

• DEQUEUE operation: Removes the element at array[front] and increments the front pointer using modulo arithmetic (front = (front + 1) % capacity). This also takes $O(1)$ time.

Since both operations perform a constant number of operations without shifting remaining elements, both ENQUEUE and DEQUEUE run in $O(1)$ time.

Therefore, option A is correct.