Answer:
The correct answers to the questions, according to research done, both on current trends in what is today Iraq and parts of Syria, where Mesopotamia used to be located, on climate and physical characteristics, and what used to be a part of Mesopotamia, would be:
A: Mesopotamia was between the Tigris and Euphrates. In fact this is the source of the name. Mesopotamia means land between two rivers, and these two rivers, historically, are the Tigris and Euphrates.
B: There was abundant annual rainfall in Mesopotamia. This was the reason why the rivers woud overflow during springtime. It is also the reason why, Mesopotamia, aside from the other regions around it, was more fertile, and able to grow crops that were impossible to grow anywhere else.
C: The rivers of Mesopotamia flooded annually. This is the reason why this particular part of this region, which in general is dessertic, was able to group crops that could not be grown anywhere else. These floodings happened one a year, during springtime.