Choose the correct option for $P$ and $Q$ in the given diagram representing population density $(N)$:

The age pyramid with a broad base indicates:

The given age pyramid for human population indicates:

What is formed by the aggregation of individual organisms of the same species?

Read the given statements carefully and select the correct ones:
$(1)$ Individuals of the same species together form a population.
$(2)$ Mortality is an important factor for population growth.
$(3)$ Natality (birth rate) is an important factor for the immediate increase in population size.
$(4)$ In commensalism,both organisms benefit from the interaction.

In India,the human population is heavily weighed towards the younger age groups as a result of: