What data structure represents an item list that operates on a first-in-first-out basis?

• A. Queue
• B. Quick Sort
• C. Recursion
• D. Relational Database

Answer: (A)

A queue is a data structure that processes elements in the order they arrive, implementing first-in-first-out behavior. You add items to the back (enqueue) and remove from the front (dequeue), so the earliest item added is the first one removed. This ordering makes queues ideal for tasks like print jobs, request handling, or buffering streams, where you want to ensure fair, ordered processing. Implementations typically support efficient enqueuing and dequeuing, keeping track of the front and back of the list. The other terms refer to different ideas: Quick Sort is a sorting algorithm, not a structure that inherently enforces FIFO; Recursion is a problem-solving technique that uses self-referential calls; a Relational Database is a storage and query system for structured data, not a specialized FIFO item list.