In the meaning of wave x it would be solid
~ 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.
