Why did the world's first civilizations develop in river valleys?

a.) the climate in river valleys was good for hunting and fishing.
b.) the land in river valleys supported agriculture.
c.) nomadic tribes could use rivers to trade with other nomadic tribes.
d.) papyrus plants grown near the river could be made into paper.

B). The land in river valleys supported agriculture.

Explanation:

The main reason why the first civilizations developed in river valleys was because the land in these valleys supported agriculture. Land in these regions tends to be very fertile, for several reasons. The land in these areas is often full of nutrients, as the river carries them when it overflows. Moreover, the proximity of water makes it easier to irrigate the crops. Finally, water usually brings a larger amount of animals, which in turn help nourish the ecosystem.

the answer is b. 300t + 3/2xt

b. sec, foreign relations