Here is a boldface CR...

Although the earliest surviving Greek inscriptions written in an alphabet date from the eighth century B.C., a strong case can be made that the Greeks actually adopted alphabetic writing at least two centuries earlier. Significantly, the text of these earliest surviving Greek inscriptions sometimes runs from right to left and sometimes from left to right. Now, the Greeks learned alphabetic writing from the Phoenicians, and in the process they would surely have adopted whatever convention the Phoenicians were then using with respect to the direction of writing. Originally, Phoenicians writing ran in either direction, but by the eighth century B.C. it had been consistently written from right to left for about two centuries.

In the argument given, the two portions in boldface play which of the following roles?
A. The first provides evidence in support of the position that the argument seeks to establish; the second is that position.

B. The first provides evidence in support of the position that the argument seeks to establish; the second presents an assumption on which that argument relies.

C. The first is an assumption that the argument concludes is unjustified; the second presents part of the grounds for that conclusion.

D. The first is evidence that forms the basis for an objection to the position that the argument seeks to establish; the second is that position.

E. The first is evidence that forms the basis for an objection to the position that the argument seeks to establish; the second is a judgment that is introduced in order to call into question the relevance of that evidence.

There's one in the purple Official Verbal Review Guide. That's the only "official" example of a boldface CR out there. They're generally 700+ level questions, so if you see any of those you are probably doing pretty well on your exam!

The answer choice A is not complete
The complet answer choice A is :
A: The first is the position that the argument seeks to establish; the second reports a discovery that has been used to support a position that the argument opposes.

The OA is B,
but the second portion is not an assumption, any guru please explain, and why is A wrong

First part conveys that: ...Greek inscriptions sometimes runs from right to left and sometimes from left to right.. later on the paragraph goes on to say that Greek was derived from Phoenicians.

Second part says: Phoenician inscriptions runs from right to left and sometimes from left to right.

It is clear that second part is an assumption on which the first part is built. Alternative A suggests otherway around. Hope this is clear.