You should always remember with Weaken questions, both in RC and in Logical Reasoning, that you're not just trying to weaken the conclusion - you're trying to weaken the link between premises and conclusion. That is, you're trying to say that the information offered in the passage does not necessarily lead to the conclusion stated in the passage. I'll get into the specifics of that in just a moment.
I believe some of your confusion may be stemming from the use of the word "authenticity" in answer choice E. The critics in the passage are not disputing the authenticity of Kingston's work - they are not calling them fraudulent or fakes - they are merely saying that Kingston's work has been produced without reference to or basis in Chinese culture and literature.
More than that, the conclusion of the passage is roughly that Kingston's work is in fact steeped in Chinese culture despite the critics saying otherwise. That conclusion would not be weakened by knowing that no critics are calling Kingston's work inauthentic. This is a little tricky, though, so I see where you're coming from.
Answer choice D is correct because if it were true, and China Men was atypical
- not like the others - among Kingston's work, then the conclusion that Kingston's work heavily uses concepts like talk-story is not proven
by the example of China Men. If none other of Kingston's works use any of the same talk-story conventions as China Men, then the assertions of the critics are not disproven by the existence of China Men, as all of Kingston's other novels wouldn't use talk-story aspects.
This one's tough, so feel free to ask any follow-up questions you have.
Hope that helps,