Which of the following is a natural disaster that can have a significant impact on human populations?

a. hurricane

b. volcano

c. earthquake

d. all of the above User: Which of the following human activities can increase the risks of flooding?

a. cultivation

b. planting trees

c. soil management

d. widening rivers

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.