Aprincipal theory in social psychology is social exchange theory. according to this theory, we will be most likely to others

when the benefits outweigh the costs

Explanation:

The social exchange theory is the theory that looks at social interaction between parties which judge the risks and benefits of an exchange by doing a cost-benefit analysis.

According to this theory the cost-benefit analysis is done by people in all types of social exchanges. If a person in a relationship gives effort in the relationship but it is not reciprocated by the other person the relationship is likely not to succeed according to this theory. So, the benefits need to outweigh the cost in order for a person to help another person.

answer:

d. because dr. laguardia selected a widely used measure, his study generalizes to has strong external validity. external validity has limited external validity. other applications of this measure.

the widely used measure that he applied to his experiment was the benton facial recognition test. it employed on to football players and as result, only players who suffered brain concussions did not pas this test. and although it has an external validity, it is limited because it isn't general to apply to other population.