prep08 求助

cquzyr

露珠脑残，看了helr大神的解释还是看不懂这道……

In a study conducted in Pennsylvania, servers invarious restaurants wrote “Thank you” on randomly selected bills beforepresenting the bills to their customers. Tips on these bills were an average of three percentage points higherthan tips on bills without the message. Therefore, if servers in Pennsylvania regularly wrote “Thank you” onrestaurant bills, their average income from tips would be significantly higherthan it otherwise would have been.

Which of the following is an assumption on whichthe argument relies?

A. The “Thank you” messages would have the sameimpact on regular patrons of a restaurant as they would on occasional patronsof the same restaurant.

B. Regularly seeing “Thank you” written on theirbills would not lead restaurant patrons to revert to their earlier tippinghabits.

C. The written “Thank you” reminds restaurantpatrons that tips constitute a significant part of the income of many foodservers.

D. The rate at which people tip food servers inPennsylvania does not vary with how expensive a restaurant is.

E. Virtually all patrons of the Pennsylvaniarestaurants in the study who were given a bill with “Thank you” written on itleft a larger tip than they otherwise would have.

求各路神仙解释一下。。。

我不懂的点是：如果客户不改变消费的习惯。。。怎么会多付钱呢？我觉得b是削弱，求鞭打求各路大神救救我这个逻辑有缺陷的人吧！