a solar eclipse, when the moons shadow comes between the sun and earth
Answer:
3
Explanation: i did the test
In urban areas, there are more people, therefore not a lot of farmland. (that eliminates C) If city buildings don't allow flood waters to recede, that could be dangerous in many ways. (So A is still a reasonable answer) If most cities are built in flood zones, there should be some form of shelter if houses aren't safe. Pollutants and diseases being carried in water are already dangerous, but easier to spread with rapid flood waters that are sweeping everywhere. So your best answer would be either A or B.
What first comes to my mind is that one or more rivers feature very prominently in these civilizations: the Nile in the Egyptian and the Tigris and Euphrates in the Babylonian.
