Which Statement Best Summarizes Why, According to the Author, Cultural

Which statement best summarizes why, according to the author, cultural relativism is nearly impossible to use?

A) Each of us belongs to only one society, and so we cannot know what people in other societies believe.
B) Each of us belongs to multiple societies or social groups, but cultural relativism does not specify which society or group we should use in evaluating actions.
C) It is often impossible to know whether your culture approves of a given action.
D) The theory makes it impossible to convince other people of moral claims.