I incorrectly chose A instead of C.

Hi @zachmorley2, Thanks for the question! The sufficient and necessary module will clear up a lot of this, so would highly recommend. But basically, “if” introduces the sufficient condition, and “only if” introduces the necessary condition. So “if you come over, I’ll make dinner” is diagrammed You come over —> I make dinner But “only if you come over will I make dinner” is diagrammed I make dinner —> You come over And so these are flipped from each other! They don’t say the same thing at all, and here, that’s what makes (C) better than (A). Hope this helps! Feel free to ask any other questions that you might have.