Why has the perennial system of irrigation replaced the basin system of irrigation for farmers near the nile river?

a. the perennial system only allows the planting of one main crop.
b. the perennial system is less dependent on the nile flood and allows the planting of multiple crops.
c. the perennial system was developed thousands of years ago.
d. the perennial system is more effective in places like egypt and northern sudan.

The correct option is B

Perennial rivers have an uninterrupted flow of water throughout the year, regardless of the season, although some perennial rivers may stop flowing during a severe drought. The perennial rivers drain a large area that forms the river basin, such as the Amazon River, which covers an area of 2.7 million square miles and is the largest basin in the world. The Congo River in Africa drains an area of 1.5 million square miles, making it the second largest river basin in the world.

by improved communication.

i'm pretty sure it would be, the mediterranean sea.