Which of the following is NOT a benefit of using functions?

As an AI language model, I cannot provide personal opinions. However, I can provide some general information.

All programming languages have functions as one of the fundamental building blocks. Functions are used to break down a program into smaller, more manageable chunks. They provide modularity and reusability, improve code readability, and make the code more organized. They help simplify complex operations and make the code easier to maintain. Therefore, all the given options have some benefits of using functions.

Option D) Increase program complexity, is not a benefit of using functions. It is the opposite of what functions try to achieve. Functions aim to simplify program complexity by breaking it down into smaller pieces.