The impact of immigration on population density is

Zero growth means :

Any species growing ...$A$... under unlimited resource conditions can reach enormous population densities in a short time. Darwin showed how even $\ldots$ $B$... growing animal like elephant could reach enormous numbers in absence of check and that characteristics of organism is called $C$

Choose the correct option for $A , B$ or $C$ respectively

Zero growth means:

Certain characteristic demographic features of developing countries are