Which of the following data structures is used to implement a priority queue?

A priority queue is a specialized data structure that allows elements to be added with a priority, meaning that when elements are removed, they are taken in the order based on their priority rather than their order of insertion. Among the options provided, a heap is the most suitable data structure for implementing a priority queue.

Heaps, particularly binary heaps, are designed to efficiently support operations that are crucial for priority queues. These operations include inserting an element, deleting the highest (or lowest) priority element, and peeking at the highest priority element. A binary heap allows both insertion and deletion of the highest priority element to be achieved in logarithmic time complexity O(log n), making it efficient for dynamic scenarios where elements are frequently added or removed.

In contrast, while binary search trees and linked lists can be used to implement priority queues, they do not provide the same level of efficiency for the necessary operations. An array can be used as well, but maintaining order according to priority would generally require reshuffling elements, making operations less efficient compared to a heap. Thus, heaps are specifically designed to meet the needs of a priority queue effectively, which is why they are recognized as the most appropriate implementation for this data structure.