Feminists argue that gender matters because

a. it is the basis of sex role theory.
b. it structures social relations between people.
c. it emphasizes natural differences that exist between men and women.
d. there are roles for which men are better suited and other roles for which women are better suited.

the answer is: B. it structures social relations between people

In every society, there is a set of expectation regarding the roles that are expected to be carried on by each gender (for most societies, the men are expected to be the leaders/protectors while the women are expected to be the nurturer)

Because of this expectation, the social relations among them also heavily affected. If this is thought since early age, people would become less likely to do something that does not fulfill their gender expectation.