The actual soil horizon with the most organic matter is the?

Which soil horizon is mostly composed of organic matter?

It is only between 5 to 10 inches thick and consists of organic matter and minerals. This is the soil layer where plants and organisms primarily live. B: This layer is also called Subsoil. It is mostly made of clay, iron minerals as well as organic matter, which has been washed down to this horizon by rainwater.

c. 4.54 x 10–12 j happens to be correct