为让版面清洁，只留下同学问的题目及正确答案，
详细题目版在此: https://goo.gl/ThZZXs
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?
B. 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.
请注意，看到 credit card logo