Since I am practicing my conditional logic diagramming, I decided to post my solutions to this problem
Maria won four-time winner
______________________
Maria trained hard
So the author is assuming something along the lines of:
If you won a four-time winner then you trained hard OR the contrapositive which is If you didn't train hard then you couldn't have won a four-time winner
(A) - Nothing about Sue -- we are only concerned with Maria
(B) - It is the reversed logic! This gives us: Maria trained hard --> Maria win four-time winner (not what we want!)
(C) - the correct answer! It gives us: Maria won four-time winner --> Maria trained hard (remember only if is a necessary condition)
(D) - Same problem with (A), we really don't care about Sue
(E) - Again.. we REALLY DON'T CARE ABOUT SUE!
Although this was probably one of those questions where you really didn't need to diagram, I just did for the sake of practice since I noticed that a lot of sufficient assumption questions included conditional logic. Any feedback would be great!