This biome has a layer of soil that can either be sandy, gravelly, or stony, depending on the type of desert. Deserts usually get at most 50 centimeters (20 inches) of rainfall a year, and the organisms that live in deserts are adapted to this extremely dry climate. Plants in deserts have adaptations to conserve water.
Are you sure these are the only answer choices? I believe the answer would be Hippocampus, but it's not up there.