In biology, the biotic factors pertain to the living components of Earth while the abiotic factors are those non-living chemicals and physical factors. The only choice that is not an interaction between biotic and abiotic factors is the third choice, "C. male elk fighting over a female".
NADP is the most abundant acceptor for hydrogen released in the Krebs cycle.
Alright, so the highest temperature at which water is most dense id 4 degrees Celcius, if it gets lower than that, water would start to expand. So at 5 degrees, it would just be rain.