Which of the following characteristics is true for pelagic fishes?

Any species growing $A$ under unlimited resource conditions can reach enormous population densities in a short time. Darwin showed how even $B$ 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.

The birth and death rates of four countries are given below. Which one will have the least population growth rate?

$Country$	$Birth\, rate$ $/1000$	$Death\, rate$ $/1000$
$M$	$15$	$5$
$N$	$25$	$10$
$O$	$35$	$18$
$P$	$48$	$41$

Exponential growth cannot be sustained for a long time due to:
$I.$ Limited space and nutrients
$II.$ Accumulation of toxic agents
$III.$ Unlimited space and nutrients
$IV.$ Accumulation of nutrient agents
Choose the correct combination of options:

Phase of accelerated growth of logistic growth curve is . . . . . . .

The unrestricted reproductive capacity in a population is called ........