I think A can be safely eliminated because the anthropologist's contention is NOT a theory that will "be underminded in the discussion of a historian’s study later in the passage", but one that will be applied to the case study in the second paragraph, as correctly stated in answer choice B. The use of the word "usefully" in B may not be perfect, but we can sense a kind of usefulness from Thus Alessandra conforms more closely to the anthropologist’s notion that personal motivation is embedded in a social context... | 
