Soil can best be described as the a. loose covering of weathered rocks and decaying organic matter.   b. sandy bottom of the ocean's floor.   c. third layer beneath the earth's surface.   d. layer of bedrock four layers beneath the earth's surface.  

The correct option is A.
Soil is defined as the upper layer of the earth in which plants grow. It is usually composed of organic material called humus and particles of rocks from which the soil is formed. Soil is typically divided into different layers which is called soil profile.

A. Loose covering of wheatered rocks and decaying organic matter.

4.a depression is the answer