Hurricane, volcano and earthquake are the natural disasters that all have the potential to wreck havoc and impact the human populations. So the correct option among all the options given in the question is option "d".
Widening rivers can be a very important cause that can increase the risk of flooding. The correct option among all the options given in the question is option "d". If the humans deliberately cut the banks and widens the river, then it can cause floods during the rainy season as the banks become weak to hold the force of water that comes in.
1. The correct answer for the first question is - d. all of the above.
Hurricanes, volcanoes, and earthquakes are all natural disasters that can have a huge negative impact on humans. The hurricanes cause big floodings and have extremely strong winds that destroy most of the things on their way. Volcanoes pollute the air with the release of toxic gases and ash, the lava flows melt everything on their way, and the eruptions deliver rain of huge rocks to fall on the surrounding area. Earthquakes have extremely fast vibrations with whom they can destroy most of the buildings without a problem.
2. The correct answer for the second question is - d. widening rivers.
With the widening of rivers the banks are becoming much weaker because their naturale fence of trees and bushes has been destroyed for this to take action. The trees and bushes both represent a physical obstacle on the surface and with their root systems hold the soil in one place as well taking in huge amounts of water for their needs. When they are gone the soil has no protection whatsoever and every flooding will cause much bigger damage than it would naturally do.
