Employees of the sports department at a television station want to measure the number of viewers for a particular exercise program. They call the homes of all the members of a nearby health club. Why might this be a biased sample?
A.The station does not include everyone in the viewing area.
B.The station does not include people all across the country.
C.People who belong to a health club may have many television sets in their homes.
D.People who belong to a health club may be more likely to watch an exercise program.