Answer:
E. Investigating how the amount of annual precipitation affects the distribution of a tree species.
Explanation:
Abiotic factors are factors in an ecosystem that are non-living. Abiotic factors include water, soil, temperature, light, and air. Among all the choices, only choice E considers an abiotic factor, which is precipitation.
Precipitation is water, and as mentioned earlier, water is an abiotic factor. The case here is the study of the annual precipitation and effects on distribution of species. The study is specific to the precipitation.
The other choices involve biotic factors, like food source, the organisms and the like.