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.
It is knowing as stellar evolution
K black hole
I think it’s correct if it’s not then I’m sorry I tried
Wind blowing across the surface of the ocean is the major mechanism that generates most ocean surface waves. the movement of two liquids with different densities creates most waves.