For similar cars and drivers, automobile insurance for collision damage has always cost more in Greatport than in Fairmont. Police studies, however, show that cars owned by Greatport residents are, on average, slightly less likely to be involved in a collision than cars in Fairmont. Clearly, therefore, insurance companies are making a greater profit on collision-damage insurance in Greatport than in Fairmont.
Which of the following is an assumption on which the argument depends?
A. Repairing typical collision damage does not cost more in Greatport than in Fairmont.
B. There are no more motorists in Greatport than in Fairmont.
C. Greatport residents who have been in a collision are more likely to report it to their insurance company than Fairmont residents are.
D. Fairmont and Greatport are the cities with the highest collision-damage insurance rates.
E. The insurance companies were already aware of the difference in the likelihood of collisions before the publication of the police reports.
现在对答案A没有疑问 想请问C是什么，我怎么觉得C也对啊！谁能解释一下？谢谢！ | 
