What statement best summarizes the argument the author makes in order to convince women to "adapt [themselves] to [their] husband"?

I would say the correct answer is D. Without her husband, a woman would lead a life of total misery.

Explanation:

In this passage, Jennings says that both nature and "mankind" have made the man superior to his wife. Some of his rights are "natural", others "acquired", but he has them all and his wife (obviously) none. It follows that a woman is utterly devastated if she chooses not to adapt and even submit to her husband.

This is not a general statement about avoidance of conflict. Nor is it about the man's social connections and influence - Jennings clearly thinks that man's power doesn't stem from social circumstances alone, but from nature too. It's not about women's education (or lack thereof) either. That part is not even mentioned.