Answer:
The is 4. Like with many things about our planet it is caused by Humans and Nature, I belive because droughts can be caused by humans and nature.
Explanation: Humans cut trees down trees , which trigger droughts to happen. Also because when humans cut a widespread of trees down just for fuel, it can potentially reduce the soil's ability to hold water ... triggering droughts to happen. But also droughts can happen just by nature.