I think it’s d mark Brainly ist plz
I think it's C i'm sorry if i'm wrong.
I believe it is the outer crust but i will do more reaserch for you :)
Answer: D. Mesopotamia
Explanation: I just took the quiz and got 100%
The Mississippi River has many small tributaries, but its primary tributaries are the Ohio River and the Missouri River. The Amazon River also has a large number of tributaries, including the Rio Negro, which is one of the largest rivers in the world in terms of volume. The Nile’s primary tributary is the Atbara River.