The bio-index number means

The impact of immigration on population density is

Which of the following statements correctly correlates with the provided age pyramids?

Emigration is:

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.

If $8$ Drosophila in a laboratory population of $80$ died during a week, the death rate in the population is