Q28:
Historian: In the Drindian Empire, censuses were conducted annually to determine the population of each village. Village census records for the last half of the 1600’s are remarkably complete. This very completeness makes one point stand out; in five different years, villages overwhelmingly reported significant population declines. Tellingly, each of those five years immediately followed an increase in a certain Drindian tax. This tax, which was assessed on villages, was computed by the central government using the annual census figures. Obviously, whenever the tax went up, villages had an especially powerful economic incentive to minimize the number of people they recorded; and concealing the size of a village’s population from government census takers would have been easy. Therefore, it is reasonable to think that the reported declines did not happen.
In the historian’s argument, the two portions in boldface play which of the following roles?
A.The first supplies a context for the historian’s argument; the second acknowledges a consideration that has been used to argue against the position the historian seeks to establish.
B.The first presents evidence to support the position that the historian seeks to establish; the second acknowledges a consideration that has been used to argue against that position.
C.The first provides a context for certain evidence that supports the position that the historian seeks to establish; the second is that position.
D.The first is a position for which the historian argues; the second is an assumption that serves as the basis of that argument.
E.The first is an assumption that the historian explicitly makes in arguing for a certain position; the second acknowledges a consideration that calls that assumption into question.
MY QUESTION: it is said that the key is C. I really don't understand. The two BFs are contradict, why C says the the first BF is a context to support the position? | 
