Norbert Kerr Conducted an Experiment in Which Participants Worked Together

Norbert Kerr conducted an experiment in which participants worked together on a task that required pumping air by squeezing a rubber bulb. In conditions in which the partner pumped enough air for the pair, the participant

A) slackened effort to avoid being perceived as a "sucker."
B) worked harder to match the partner's performance.
C) experienced the Ringelmann effect.
D) engaged in free riding.