$A$ biologist studied the population of rats in a barn. He found that the average natality was $250$, average mortality $240$, immigration $20$ and emigration $30$. The net increase in population is

Which age group of organisms constitutes the pre-reproductive population?

The attributes of birth rate and death rate are not applicable to which of the following?

Under a particular set of selection pressure,organisms evolve towards the most efficient reproductive strategy. For example:
$A$) Oysters produce a large number of small-sized offspring.
$B$) Mammals produce a small number of large-sized offspring.
In the light of the above statements,choose the correct option.

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

The shape of the pyramids reflects the growth status of the population. Identify the type of age pyramid represented below for human population.