Which is the uppermost layer of soil?

• A. Subsoil
• B. Leaching
• C. Topsoil
• D. Parent material

Answer: (C)

Topsoil is the uppermost mineral layer of soil where most nutrients and organic matter collect, and where plant roots grow most heavily. This layer supports plant life because it holds the decayed material from living things, giving plants access to the nutrients they need. Subsoil sits below it and has fewer nutrients, while parent material is the original rock or sediments beneath the soil, and leaching is the process that moves minerals downward through the soil profile. Because topsoil is the highest layer that directly supports growth and nutrient exchange, it is the correct choice.