To be honest, all of those sound applicable. But since there isn't an all of the above answer, I'd say your best bet is either A or D. <span />
Answer:
Ah depressed teenager thingy.
It helps in understanding which crop should be cultivated on a particular land.
It also helps in gaining information about how agriculture can be done in poorer soils.
It gives information about the nutrient quality of the soil.
This avoids wastage of capital on the cultivation of unsuitable crops.
It also helps in controlling pests and insects.
나는 공부하고 있습니다.
Hope this helps,
