All API calls return a value.

This question is asking if every time you use a MySQL API call, you'll always get something back as a result.
Think of it like asking a question. When you ask a question, you expect an answer, right?
The same goes for API calls – they're like questions you're asking the MySQL database.
So, the answer is True.
Even if the answer is "nothing found" or an error message, you still get some kind of response.