Which choice forms the organic portion of soil?

microorganisms

dead plants

clay

sand

The dead plants form the organic part of the soil.  This is because when plants die off they become dirt and mulch which is good for the plants. This is why people make a big deal out of compost. It is because it is healthy and organic for plants.

Answer:

Dead plants form the organic portion of the soil.

Explanation:

Plant bodies and animal bodies are rich in carbon compounds and when they die their body remains will contain these compounds. Soil contains various microbes that act on the dead remains and break down the organic compounds within the remains.

The decomposition process releases carbon, nitrogen, phosphorous etc that make up the organic compounds.

Decomposition of plant bodies is termed as composting. Composting releases carbon in greater amounts into the soil. The inorganic substances released after decomposition can be used by plants and other autotrophs for nutrition.