Question

What layer of soil is closest to the surface?

Answer 1

O layer

Explanation:

O layer or organic layer. It is dominated by organically rich matter, consisting of undecomposed or partially decomposed plant materials. Since atmosphere (oxygen) interacts with this layer, decomposition takes place here.

Underneath of O layer, A layer exists. It is largely mineral soil developed from mother (parent) material. Organic layer leaching from O layer gives this layer a distinctive dark color.