I believe the answer you are looking for is: A. They have drought, tornadoes, and insect swarms.We can rule out D straight away because we know that, by definition, plains or fields are not densely populated.
The forests and lakes option doesn't stick either. This is a better description for the North East I think.
But what gives it away is the words "drought" and "tornado" more than anything.
The high plains are susceptible to periodical drought, and the South East of the Great Plains is known as tornado alley because it has the highest percentage of tornadoes anywhere on earth.