Deserts are found in bands on earth's surface.
a. one
b. two
c. three
d. four

The correct option is B.
A dessert refers to a vast land with little or no vegetation and less than 250 mm of rainfall on a yearly basis. Approximately one-third of the earth surface is covered by desert regions and deserts can be found on every continent in the world. Deserts are formed by atmospheric conditions which prevent rainfall. Most deserts can be found in TWO bands around the earth surface; the first one is along the Tropic of Cancer in the Northern hemisphere while the second one is found along the Tropic of Capricorn in the Southern hemisphere.

The right answer is c.sandstone.