I think it's a horrible question --- why would you put anything in a JSP file if it didn't have some relation to the output ??? Technically the include directive just does a static include of some snippit into your JSP file, but since it's static and output streams are only modified at runtime, I suppose, technically speaking, it doesn't modify the output, since there's no output at compile-time.
Blah. Just chalk it up as a stupid question and move on. You won't find questions like this on the exam. Just know what the directives are, why you use them, what the results are, and that's it.