Answer: 4) It protected against invasion from the west.
Step-by-step explanation:
The Nile was the "lifeblood" of ancient Egypt, a river of crucial importance for the emergence and development of ancient Egypt. The source of water, food, and frequent flooding that left fertile soil are ideal conditions for the rise of civilization.
However, the Nile was not a barrier to the war on Egypt, neither from anywhere in the world nor from the west. The Romans marched on this side of the globe, not the territory of Egypt, and put it under their control.