Answer:
A.Radiation is the answer
Temperature, sunlight and water are all examples of the abiotic components of the ecosystem.
The ecosystem is the interaction and dynamic interdependent exchange of the biotic and abiotic factors of the environment. The biotic factors are the life or living organisms that live in the said environment. While the abiotic factors are those for example, soil, water, wind, air, minerals and etc
Commensalism is an interaction in which one individual benefits while the other is neither helped nor harmed. Example: Orchids (example of epiphytes)
I believe that the answer would be Region D!
So the answer should be A!
Here you go (if you need more information, let me know!):