Deserts Typically Occur in a Band at 30 Degrees North

Deserts typically occur in a band at 30 degrees north and south latitude because

A) descending air masses tend to be cool and dry.
B) trade winds have a little moisture.
C) water is heavier than air and is not carried far over land.
D) ascending air tends to be moist.
E) these locations get the most intense solar radiation of any location on Earth