Which best describes an array?

An array is fundamentally a data structure that allows you to store multiple items under a single identifier, enabling the grouping of related data elements. This is particularly useful in programming when you want to handle a list of items, such as a collection of integers, strings, or objects, because it simplifies code organization and access.

Each element in an array can be accessed individually using an index, which typically starts at zero in many programming languages, providing a clear and efficient way to refer to the single items within that overarching structure. This definition aligns perfectly with the characteristics of an array, highlighting its use of a singular identifier to manage multiple data items simultaneously.

The other options describe concepts that don't accurately capture the essence of an array. For instance, key/value pairs pertain more specifically to structures like dictionaries or maps, which are not what an array represents. Sequential formats and changing variable types are different concepts altogether, as arrays maintain fixed positions for their items and focus on data organization rather than variability or order.