GWD31-22-14关于付小费问题

Studies in restaurants show that the tips left by customers who pay their bill in cash tend to be larger when the bill is presented on a tray that bears a credit-card logo.  Consumer psychologists hypothesize that simply seeing a credit-card logo makes many credit-card holders willing to spend more because it reminds them that their spending power exceeds the cash they have immediately available.

Which of the following, if true, most strongly supports the psychologists’ interpretation of the studies?

1. The effect noted in the studies is not limited to patrons who have credit cards.

2. Patrons who are under financial pressure from their credit-card obligations tend to tip less when presented with a restaurant bill on a tray with credit-card logo than when the tray has no logo.

3. In virtually all of the cases in the studies, the patrons who paid bills in cash did not possess credit cards.

4. In general, restaurant patrons who pay their bills in cash leave larger tips than do those who pay by credit card.

5. The percentage of restaurant bills paid with given brand of credit card increases when that credit card’s logo is displayed on the tray with which the bill is prepared.

答案是B，可能是我没看懂题，现金和支票的那个夫的更多阿？

I don't get it either.

Is there anything wrong with the statment or the question?

If the question is changed to "Which of the following, if true, most seriously weakens the psychologists’ interpretation of the studies?"

Then the answer should be C.

还是不明白，哪位大牛给讲讲。