Which statement terminates the execution of a function?

This question is asking about how to stop a function from running in MySQL. Let's break down the options:
Option A: BEGIN...END
This defines a block of code within the function. It doesn't actually stop the function.
Option B: RETURN
This is the correct answer! RETURN is used to immediately stop a function and optionally send back a value.
Option C: ITERATE
This is used inside loops to jump back to the beginning of the loop, not to stop the entire function.
Option D: LOOP
This creates a loop within the function, but it doesn't stop the function.
So the answer is Option B: RETURN.