Define/Explain: Census.

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.

In the given figure,which factors are responsible for the increase in population density?

Which of the following are useful for measuring population density (size)?
$(a)$ Numbers
$(b)$ Biomass
$(c)$ Pug marks
$(d)$ Height

Which characteristic is responsible for an increase in population?

In the given diagram,identify $a, b, c,$ and $d$. Specifically,identify $b$ and $c$.