A polling company has been hired to determine the approval rating for a local member of Congress. The company completed the poll by creating a survey and instructing representatives to stand outside a mall to give the survey to departing shoppers. The polling representatives were also instructed to take responses only from participants who were male. Then, the polling company published a report which put the congressperson's approval rating at 79%. Why could this sample be biased?

A. The representatives of the company were male.

B. The representatives of the company only gave the survey to a select group, as opposed to a wider, more representative sample.

C. The survey questions were biased toward the congressperson's opponent.

D. The mall was outside the congressperson's local area.