What is the formula for exponential population growth?

Members of a certain insect species show a massive increase in population during the rainy season,decrease in number as winter approaches,and disappear by the end of winter. What does this indicate?

If the population at time $t$ is $N_t$,then its population at time $t + 1$ is . . . . . . .

Which of the following is $NOT$ applicable to population growth?

The carrying capacity of the Earth for the human population is estimated to be approximately:

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.