Answer:
The correct answer is - option 2. earthworm.
Step-by-step explanation:
Soil aeration is one of the major factors that help in the productivity of the soil, it is the phenomenon that exchanges the gases between the atmosphere and soil. Microbes and plants leads to change in the oxygen and carbon dioxide in the soil. Volume of the macropores, oxygen, CO2, redox potential helps in the determining the soil aeration.
Earthworms are the natural way of the help in the status of the soil aeration as they help in the increasing the volume of the macropores in the soil asnd help. They help in increasing soil porosity which increases the air and gases in the soil.