(E) says, "Ethnographers studying the !Kung interview !Kung women other than Nisa and find that most of them report experiences similar to those of Nisa."
In order to bolster the author's contention, we're looking to show that !Kung women's life experiences bear resemblances to women's life experiences in general. The fact that Nisa's experiences are similar to other !Kung women would not help us accomplish this goal, as it's possible that most or all !Kung women have the same types of experiences as each other, but they're far different from women's experiences in other parts of the world. Thus, we can get rid of (E).
Does this make sense? Let us know if you have any other questions!