(A) is the CORRECT answer, because both passages show through the development and higher prevalence of tooth caries how humans moved from a hunter gatherer society to an agricultural. Lines 1-5 clearly state this in Passage A, and, in Passage B, lines 32-38 discuss how increased caries is evidence showing how the early inhabitants of Ban Chiang became increasingly dependent on agriculture.
(B) is incorrect because we are not talking about the "overall health" of human populations. We are discussing the development of agriculture and its impact on tooth decay.
(C) is incorrect because we are not discussing "strictly agricultural societies." In fact we are discussing the evolution from hunter gatherer societies to agriculture dependent societies.
(D) is incorrect because neither passage discusses when the first agricultural society arose.
(E) is incorrect because neither passage focuses on the "extent" to which pre-agricultural populations were able to obtain carbohydrate-rich foods.
Hope that helps! Let me know if you have any other questions!
