Which of the following statements is true regarding individuals of the same species?

The changing nature of a population is called:

The crude number of births by a population per unit time is called:

$A$ population is said to achieve demographic transition, if

Which one of the following is $NOT$ a characteristic of a population?

Read the following statements and select the correct option with respect to population attributes:
$(a)$ Population density is necessarily measured in numbers.
$(b)$ Tiger census is often based on pug marks and fecal pellets.
$(c)$ Biomass is not a meaningful measure to know population size.
$(d)$ Size of a population for any species is not a static parameter.