请教新版PREP2-89，谢谢！

89.   (29334-!-item-!-188;#058&003870)

Which of the following most logically completes the argument?

The growing popularity of computer-based activities was widely predicted to result in a corresponding decline in television viewing.  Recent studies have found that, in the United States, people who own computers watch, on average, significantly less television than people who do not own computers.  In itself, however, this finding does very little to show that computer use tends to reduce television viewing time, since __________.

A. many people who watch little or no television do not own a computer

B. even though most computer owners in the United States watch significantly less television than the national average, some computer owners watch far more television than the national average

C. computer owners in the United States predominantly belong to demographic groups that have long been known to spend less time watching television than the population as a whole does

D. many computer owners in the United States have enough leisure time that spending significant amounts of time on the computer still leaves ample time for watching television

E. many people use their computers primarily for tasks such as correspondence that can be done more rapidly on the computer, and doing so leaves more leisure time for watching television

答案居然是C。让人抓狂啊。。。是不是答案错了？