Answer:
c. composting
Step-by-step explanation:
The composting is a process through which organic matter has been decomposed. This is done in order to produce lot of biomass, mix it with ground, rocks, ashes, and create a very fertile soil that will contribute to much better plant growth. This process is used for the agriculture and horticulture, but it is in no way connected to the improvement of the air quality, nor it is a technological thing.