The authors of your text tell a story about abraham lincoln in which lincoln ordered a coach to stop so he could save some piglets from drowning. lincoln claimed that he helped because "i should have had no peace of mind all day had i gone on and left that suffering old sow worrying over those pigs." lincoln argued that he was helping because of

a. altruism.

b. self-interest.

c. social exchange concerns.

d. the reciprocity norm.