Question

which survey is most likely affected by bias?
○ a survey of teenagers about their favorite colors
○ a survey of students about vacation policies in a school district
○ a survey of supermarket shoppers about products they would like to see added
○ a survey of bike riders on whether they wear helmets

Explanation:

Bias in surveys often arises when respondents have a personal stake or incentive to answer in a way that does not reflect the truth. Bike riders may be less likely to admit they do not wear helmets due to social desirability bias (wanting to appear responsible or avoid judgment), whereas the other surveys involve neutral topics where respondents have little reason to misrepresent their answers.

Answer:

a survey of bike riders on whether they wear helmets