Biotic Factors are any living components that affect other organisms, and since soil is not alive (soil is an abiotic factor) then you can eliminate A., B., and C. D is the answer choice that has only biotic examples.
Trichomes increase the chances of survival for plants living in areas with infrequent rainfall.
If a plant in a very rainy place had trichomes, it would probably adapt and remove them as time passed as they are unnecessary.
It contracts hope that helps