Explanation:

A - R; B - Q; C - P; D - S

Bird and bat wings are analogous — that is, they have separate evolutionary origins, but are superficially similar because they have both experienced natural selection that shaped them to play a key role in flight. ... Interestingly, though bird and bat wings are analogous as wings, as forelimbs they are homologous.

Mendel observed that the F2 progeny of his dihybrid cross had a 9:3:3:1 ratio and produced nine plants with round, yellow seeds, three plants with round, green seeds, three plants with wrinkled, yellow seeds and one plant with wrinkled, green seeds.

Natural selection is the process through which populations of living organisms adapt and change. Individuals in a population are naturally variable, meaning that they are all different in some ways. This variation means that some individuals have traits better suited to the environment than others.

The wing of a bird is a modified forelimb. It is adapted for an aerial mode of living i.e. used for flying. Whereas, the forelimb in humans is called an arm. It is used for various purposes like holding, clutching, lifting, writing, etc.