Environmental resistance includes factor

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

Population evolve to maximise their reproductive fitness also called Darwinian fitness with

Give differences: Natality rate and Mortality rate

$A $: Under unlimited resource condition a population can show a exponential growth curve.
$R$ : $A $maximum possible number of individuals can always be supported when enough resources are available
 

Rapid decline in a population due to high mortality rate is