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.
Flood waters can be channeled to provide irrigation is true about the development of farming in Summer. The correct option among all the options that are given in the question is the last option or option "D". Without adequate amount of water, it is not possible to farm in the summer months.
The answer is D. It happened because of ethnic tensions that led to Genocide against the Tutsi which was organized by the members of the Hutu majority government. It killed approximately 500,000 to 1,000, 000 Rwandans between April and mid July of year 1994.
