D.
This is self-regulation because when the population of the insects becomes too large, it regulates itself and starts to decrease due to a shortage of resources.
Chemical equations are to be balanced to be able to follow the law of conservation of mass where it says that mass cannot be created or destroyed. Reactions should be that the mass of the reactants is equal to the mass of the products.
Lets say foxes hunt rabbits. If their are too many foxes then they will compete for the rabbits. The rabbits get outnumbered by the amount of foxes so the foxes kill all the rabbits and the rabbits could eventually go extinct.
The formula of Density is known as:
Density = mass/volume
Units: g/cm^3
Hope this helps!
