What is a common characteristic of functions in a programming library?

Functions in a programming library are commonly grouped because they relate to the same purpose or functionality. This organization allows developers to efficiently access a set of tools designed to perform specific tasks or solve particular problems within a given domain. For instance, a library focused on data manipulation will include functions for sorting, filtering, and transforming data, all geared toward that common goal. This characteristic enhances code readability, maintainability, and usability, enabling programmers to locate and utilize relevant functions easily when addressing specific challenges in their code.

The other options do not accurately depict the nature of functions in programming libraries. Functions may certainly perform a variety of operations, including mathematical, text processing, or even network communication, but being unrelated or confined to a specific type of data processing is not typical of a well-structured library. Instead, they are organized around thematic or functional attributes to facilitate ease of use and relevance in practical applications.