I dont know how old Eli is but here are some
ride a bike instead of driving a car
plant trees
slow down on use of water/electricity
The right answer is C
This process is called anaerobic respiration. It doesn't need dioxygen to occur (it can happen with or without O2).
Anaerobic respiration is a mechanism in which electrons pass through a chain of transporters whose final acceptor is a mineral substance other than oxygen, unlike aerobic respiration where the final acceptor is dioxygen. The final acceptor may be the nitrate ion (as in the case of Pseudomonas), carbon dioxyde or the sulfate ion.
Some bacteria (Pseudomonas) are able, anaerobically, to reduce nitrates to nitrites and then, depending on the case, to dinitrogen (with the enzyme Nitrate reductase A).
NO3- ==> NO2- ==> N2.
~ B - Adding wood to a burning fire to increase the heat.
A is kind of like a reaction to negative feedback - it's too hot, so cooling down.
C is like turning the air conditioner off. It's cool enough.
B on the other hand adds something to the whole by reinforcing it. The fire is a metaphor for the writer's self-esteem, ego, good-feelingness, what-have-you.