Becasue all the code options povide produce an error or NULL. Now if you think that an error or NULL is the expected result, then one of them may be right and it might be C. I thought that the expected result was some useful data, not an error message or NULL, so that none of the suggested answers produced the expected result. I may have been wrong - maybe case C produced the expected error message, in which case I have to ask why that error message rather than the result of A or B is the expected result. Do you have an answer for that? Or are you taking the rather arrogant view that because you don't like the question you will reformulate it to mean something different (perhaps something more fully specified) rather than refer it back to the poser?