What is one of the main features of a subprogram?

A subprogram, often known as a function, method, or procedure, serves as a distinct unit of code designed to encapsulate specific functionality. This encapsulation allows the subprogram to perform a particular task, which aids in organizing and streamlining code within larger programs. By breaking down complex tasks into smaller, manageable parts, subprograms enhance code readability, maintainability, and reusability.

The inclusion of a subprogram enables developers to call the same piece of code multiple times throughout a program without rewriting it, promoting a DRY (Don't Repeat Yourself) coding philosophy. Moreover, encapsulating functionality helps in managing complexity, as it allows programmers to focus on one part of the program at a time.

Other options present characteristics that do not accurately represent the essence of subprograms. For instance, subprograms can be called multiple times, are usually designed to have a single entry and exit point for clarity, and while error handling is important, it is not a defining feature of subprograms specifically. Therefore, encapsulating specific functionality is a defining characteristic that solidifies the role of subprograms in software design and development.