Which of the following horizons has the most fertile soil? a- a horizon b-b horizon c-c horizon d- o horizon

A  A-horizon

Explanation:

The A Horizon is present below the O-horizon. The A-horizon is usually the top or first layer of the soil it is also called the topsoil. This soil zone is formed due to accumulation of organic matter and nutrients. It contains most of the organic matter. Thus, A-horizon has the most fertile layer of soil.

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.