Which statement correctly describes a queue operation?

• A. Enqueue adds to the rear; dequeue removes from the front.
• B. Enqueue adds to the front; dequeue removes from the back.
• C. Enqueue and dequeue both add elements.
• D. Dequeue adds to the rear.

Answer: (A)

A queue follows First-In-First-Out: elements are added at the rear and removed from the front. Enqueue is the operation that inserts a new element at the rear, so it sits behind all elements already in the queue. Dequeue is the operation that removes the element at the front, the oldest one that entered the queue. This pairing preserves the order of processing as elements flow from front to rear.

The other descriptions don’t fit this behavior. If enqueue added to the front, or dequeue removed from the back, you’d be using the opposite ends for insertion and removal, which isn’t how a typical queue operates. Saying both operations add elements would ignore the removal action of dequeue. And saying dequeue adds to the rear contradicts its purpose of removing an element.