Which of the following techniques enhances code reusability?

Writing multiple functions that tackle small subproblems enhances code reusability because it allows each function to perform a specific task independently. This modular approach means that once a function is created, it can be reused in different parts of the program or even in future projects without the need to rewrite code. By breaking down a larger problem into smaller, manageable pieces, each function can be tested and debugged individually, which simplifies maintenance and increases collaboration among programmers.

In contrast, using specific values in functions instead of parameters creates situations where functions can only be used in very limited scenarios, thus reducing reuse. Minimizing the length of code arbitrarily does not necessarily make the code more reusable; rather, it can lead to less readable and maintainable code. Lastly, relying on a single global variable for all data can lead to complications such as unintended side effects and difficulties in tracking data flow, thereby making the code less reusable.