In a Mendelian population,genetic drift occurs in which of the following?

Observations from England support evolution by natural selection. Before industrialization, $P$ moths were more abundant on trees, whereas after industrialization, $Q$ moths were more abundant. Identify $Q$.

In the case of the peppered moth $(Biston \text{ } betularia)$, the black-coloured form became dominant over the light-coloured form in England during the industrial revolution. This is an example of:

The frequency of a character in a population is found to be increasing when:

In a population of plants,some were extremely tall,and the remaining were extremely dwarf. No plants of the population showed intermediate height. The type of operation of natural selection in the above case is

The diagram below shows the process of natural selection. Choose the correct option for $P, Q$ and $R$.