The evolution occurring at a genetic level is called

The correct option is D Microevolution
Microevolution is the change in allele frequencies that occur over time within a population. This change is due to four different processes: mutation, selection (natural and artificial), gene flow, and genetic drift. Thus, option D is correct. Macroevolution is evolution on a scale of separated gene pools. Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population. Thus, option A is wrong. Megaevolution describes the most dramatic events in evolution. It is no longer suggested that the evolutionary processes involved are necessarily special, although in some cases they might be. Whereas macroevolution can apply to relatively modest changes that produced diversification of species and genera and are readily compared to microevolution; megaevolution is used for great changes. Thus, option B is wrong. Inorganic evolution is the theory of the creation of the universe, not of the species of animals found on earth (i.e., organic evolution. Thus, option C is wrong.