The first answer says "If Nemo is a fish, then he swims". That makes sense. Then the second one says "If Nemo does swim, then he is a fish". That would make sense, but if my name was Nemo, I can swim. That doesn't mean I'm a fish. The the third one says "If Nemo is not a fish, then he doesn't swim". That doesn't make sense. Say my name is Nemo. I'm not a fish. I can swim though!
You haven't given the answer options, however I assume it will be written in this form. I.e. the number of cupcakes still needed is just the total number of students (32) minus the number that Jenna bought (14).
