GWD3-Q9:

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.

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

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.

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

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

E  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.

答案选B，WHY？？？

THANKS!!

原来是这个意思...

this quetion has been disscussed for a hundred of times.

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