Which of the following describes topsoil?
a. A layer of material placed over bare soil, usually made up of partially composted organic materials such as shredded hardwood, tree bark or leaves
b. Sturdy construction and landscaping aggregate that is commonly used under building pads, bases, driveways, etc.
c. A geosynthetic material (often plastic strands or strips joined in a grid) used to reinforce soils and aggregates
d. The Nutrient rich layer that provides a growing media for vegetation, overall soil structure, and regulation of moisture content.