A poll claims that Mayor Harkins will receive 60 percent of the vote in the upcoming mayoral race. The poll was taken over the weekend at three different malls in which over 250 people were asked their preference. Most of the people claimed to be registered voters, but the pollsters didn't ask for proof of registration.

The situation above represents an example of selection bias.

Explanation:

Selection bias occurs when there is a failure in the selection of factors, individuals and information for a given study.

In the case shown in the question above, we can see that an electoral survey was carried out, where voters did not prove whether they had registration for voting, therefore the information given by them, could not be relevant to the study in question. In this case, we can say that there was a failure in the selection of information, which may result in an inaccurate and incorrect study.

i don't know sorry i cannot read a novel in 30 min.

explanation:

but just in case i think the answer is b.