Why are functions useful?

Functions are useful primarily because they make code shorter and more readable. By encapsulating a specific set of instructions within a function, a programmer can avoid redundancy, as the same function can be called multiple times from different parts of the code. This practice not only reduces the total amount of code written but also enhances readability, as it allows the code to be structured in a way that clearly conveys the overall logic of the program.

Moreover, using functions promotes modularity, which enables easier troubleshooting and debugging, since individual functions can be tested in isolation. A well-named function can also provide insight into its purpose, making it easier for others (or the same programmer at a later time) to understand the code at a glance.

In contrast, the other options do not accurately reflect the primary benefits of using functions. They do not provide automatic corrections for syntax errors, they cannot prevent logical errors, and they are not inherently required for loops to function, even though loops can certainly use functions to operate more effectively.