What is a function prototype?

A function prototype serves as a declaration that specifies essential details about a function before its actual implementation. It includes the function's name, the types and order of its parameters, and its return type. This prototype allows the compiler to understand what kind of function to expect, helping in type checking and ensuring that functions are called correctly with the appropriate types of arguments.

This is particularly useful in C programming, where the function might be defined after it is called in the code. By providing a prototype, you allow for the compiler to check for consistency and correctness throughout the program. The other options, while related to functions, do not effectively capture the concept of a function prototype. Only option B accurately describes the necessary components and purpose of a function prototype in C programming.