Conclusion: Because Maria trained hard, she could beat Sue, who was champion for 4years.
Assumption: If Maria did not train hard, she couldn't beat Sue in the race.
(A) Sue did not train as hard as Maria trained.- Negating this statement does not break conclusion.
(B) If Maria trained hard, she would win the sailboat race.- Cannot tell about this based on given premise.
(C) Maria could beat a four-time winner only if she trained hard.- Yes, clearly the assumption.
(D) If Sue trained hard,
...
Assumption: If Maria did not train hard, she couldn't beat Sue in the race.
(A) Sue did not train as hard as Maria trained.- Negating this statement does not break conclusion.
(B) If Maria trained hard, she would win the sailboat race.- Cannot tell about this based on given premise.
(C) Maria could beat a four-time winner only if she trained hard.- Yes, clearly the assumption.
(D) If Sue trained hard,
...





