The correct answer is - D. A drought kills all the plants in an area, leaving bare land.
If there's such a big drought that will manage to kill off all the vegetation in an area and leave bare land behind it, than the land will be degraded in no time. Once the land is left without its natural protection that the roots of the vegetation provide, the land will be exposed to high rates of and erosion. The erosion will be very quick and the top layers of the soil will be moved away with every wind and rainfall that will appear. That will degrade the land to a very high degree, making it totally unusable and it will need lot of time to eventually recuperate.
