The charge that Colette's novels are indifferent to important moral questions is unfair. The author supports this by saying that each of her novels is a poetic condensation of a major emotional crisis in ordinary person's life. Emotional crises almost always raise these important moral questions.
What is the unstated necessary premise here?
Take answer choice B and negate it. See if it weakens the argument.
"A novel that poetically condenses a major emotional crisis does have to be indifferent to the major emotional questions raised by that crisis."
If this is the case, then her novels do not raise major emotional questions. And the charge was fair. Destroys the argument.
Let's examine answer choice E. (negated)
Colette's purpose in poetically condensing emotional crises in the lives of characters in her novels was not to explore was to explore some of the important moral questions of her time.
Whatever her purpose is irrelevant. We only want to know whether she did raise the questions or not to determine whether the charge is fair or unfair. If she did not intend to raise these moral questions, but inadvertently did anyways, the charge is still unfair and the argument is not weakened.
I hope this helps. Please let me know if you have any other questions.