It would not be surprising to discover that the trade routes between China and the West were opened many centuries, even millennia, earlier than 200 B.C., contrary to what is currently believed. After all, what made the Great Silk Road so attractive as a trade route linking China and the West—level terrain, easily traversable mountain passes, and desert oases—would also have made it an attractive route for the original emigrants to China from Africa and the Middle East, and this early migration began at least one million years ago.

Question: That a migration from Africa and the Middle East to China occurred at least one million years ago figures in the above reasoning in which one of the following ways?
Options:
A. It is cited as conclusive evidence for the claim that trade links between China and the Middle East were established long before 200 B.C.
B. It is an intermediate conclusion made plausible by the description of the terrain along which the migration supposedly took place.
C. It is offered as evidence in support of the claim that trade routes between China and the West could easily have been established much earlier than is currently believed.
D. It is offered as evidence against the claim that trade routes between China and Africa preceded those eventually established between China and the Middle East.
E. It is the main conclusion that the argument attempts to establish about intercourse between China and the West.
Answer: "C"