What is the primary factor for population growth?

Which of the following is true for $r$-selected species?

In which of the following is exponential growth observed?

Read the following statements and determine how many of them are correct:
$(1)$ Population is the total number of individuals of a species in a given area at a given time.
$(2)$ Developed countries show a low birth rate.
$(3)$ An equal proportion of reproductive and post-reproductive age individuals indicates a stable population.
$(4)$ In the presence of limited resources,the growth curve is sigmoid ($S$-shaped).

When will the population growth rate be equal to zero following the logistic model? The logistic model equation is given as: $dN/dt = rN(1 - N/K)$

If a population growing exponentially doubles in size in $3$ years,what is the intrinsic rate of increase $(r)$ of the population?