The return statement in JavaScript functions is:

In JavaScript, the return statement is indeed optional, meaning that you do not have to include it in every function you write. When a function does not have a return statement, it will return undefined by default. This allows for flexibility in function design, where some functions perform an action without needing to send a value back to the caller.

Additionally, return statements can only be utilized within the scope of a function. They cannot be employed outside of a function context, as that would lead to a syntax error. This reinforces the idea that the return statement is closely tied to function execution, making it possible to pass a value back to the part of the program that invoked the function.

The other choices do not accurately represent the nature of the return statement in JavaScript. For example, it is not required for all functions, as mentioned. Furthermore, it does not have the capability to declare variables; variable declarations are handled through keywords like var, let, and const. Lastly, the return statement does not pertain to loop execution, as it serves a specific role in function execution. Overall, option B effectively captures the essence of how the return statement functions in JavaScript.