The correct answer is B.
The main idea of the text is that not all cultures consider sex differences as we do. There are three major details in this paragraph that support this idea:
The first one is that the Arapesh people believe that men and women are equal in temperament.
The second one is that, for Mundugumor people, men and women are equally as fierce.
And the first one is on the Tchambuli tribe, men and women have different temperaments and the sex roles are interchanged.