What type of data structure stores elements in a first-in, first-out (FIFO) order?

The type of data structure that stores elements in a first-in, first-out (FIFO) order is indeed a queue. In a queue, the first element added to the structure is the first one to be removed, which mimics the behavior of a line in real life — the first person to get in line is the first one to be served. This is essential for various applications, such as task scheduling, where processes need to be managed in the order they arrive.

A stack, on the other hand, operates on a last-in, first-out (LIFO) basis, where the last element added is the first one to be removed. Arrays are simple collections of elements that can be accessed randomly via indices but do not inherently enforce any specific order for inserting or removing elements. A tree structure is more complex and involves nodes with parent-child relationships, which also do not guarantee a FIFO arrangement.

Understanding these distinctions helps clarify why a queue is the structure that aligns with the FIFO principle.