What is one advantage of using functions in programming?

Using functions in programming offers a significant advantage as they allow code to be reused without needing to rewrite it. This characteristic promotes more efficient coding practices; once a function is defined, it can be called multiple times throughout a program. This not only streamlines the development process but also reduces the likelihood of errors since any updates or bug fixes to the function need to be made in just one place rather than in every instance of the code where similar operations are performed.

This reuse capability also enhances readability and maintainability of the code. When functions are employed, programmers can break down complex tasks into smaller, manageable pieces, making it easier for others (or themselves at a later time) to understand the program's flow and functionality. This modular approach is a cornerstone of good programming practice, facilitating collaboration and ensuring that code can be tested independently for reliability.

Other options present misconceptions: increasing the amount of code contradicts the efficiency gained from reusing functions, while complexity typically arises from poor function design rather than functions themselves. Additionally, defining functions each time they are used negates the benefit of having reusable code, which undermines the primary purpose of functions.