The answer to your question is D. Reactants
Abiotic factors are things that aren't living that effect an environment, like pH (how acidic the soil is), the temperature, amount of light, and so on. These can effect a population by making it more difficult to survive, perhaps creating more competition over available resources and so on. So for example, if the soil is really acidic in an area, a population of plants may not be able to grow well in that environment.
B. Stems absorbed water and minerals from soil
Hope this helps! :)
