Answer:
The correct answer is C) The Tigris and Euphrates
Explanation:
A and B are not correct because Nile is totally to the west, so this can't be a correct answer.
D is also not correct because Persian Gulf is to the south in contrast to Ur.
C is correct as Ur is located in the Southern part of Mesopotamia, so when they traveled north they were moving along two greatest rivers of Mesopotamia.
The correct answer would be D. footnote