The question says, "The flawed reasoning in which one of the following arguments most closely resembles the flawed reasoning in the argument above?"
You asked about (A) vs. (C).
(A) says, "If the people who inhabited the valley for so long had been invaded, or if there had been a dramatic climatic change, there would have been changes in the valley's architecture. But architecture in the valley remained the same throughout their stay. Thus, the valley people must not have been invaded at any time during their stay."
The problem with (A) is that in its sufficient condition, there is an "or."
Invaded or Dramatic Climate Change - >Changes in valley's architecture
This means that if we take the contrapositive, then neither or the sufficient conditions would occur. The argument says that the necessary condition didn't occur, so then we know that neither sufficient condition occurs. This is a valid argument, so there's no way it can be the correct answer.
(C) says, "If the company had succeeded in selling its subsidiaries and used the cash to purchase the new patent, its stock price would have doubled in the last two years. But the price of the stock did not increase in that time. Thus, the company must have failed to sell its subsidiaries."
With (C), the premise structure of it and the stimulus are identical. (C)'s conclusion makes the claim that the company failed to sell its subsidiaries. However, there were to sufficient conditions. It's possible that the company may not have used the cash to buy the new patent. This flaw mirrors the flaw we see in the stimulus, so it's the correct answer choice. Both the stimulus and (C) have two sufficient conditions. The necessary condition is failed, which means that at one of the sufficient conditions was failed, but not necessarily both.
Does this make sense? Let us know if you have any more questions!
