In the sentences, there is an error. Pick the option containing error as the answer. P. We lived in very small groups, about 50 people, groups that never really got larger than 150. Q. They can cheat on the group with impunity. R. So when you start having anonymous strangers in groups, what that means is that people can free ride on the group. S. Azim Shariff, a psychology professor and author, says, “For the vast history of our species, we didn't live in large groups. T. And the reason for that is because from a genetic standpoint, we’re only built to be able to cooperate with so many people as we can know well.