Answer:
A. It is evolutionary change on a large scale often following major global changes and mass extinctions.
Explanation:
Macroevolution is concerned with large-scale evolutionary changes that span significant geological timespans and may give rise to new species, genera, families, etc.. Microevolution is therefore relatively small scale changes that takes place within species while macroevolution is dramatic changes at the genetic and phenotypic level which results in new forms of life. They mostly occur in response to significant events that shape the environment and open new evolutionary niches like mass extinction events. For example, macroevolution which occurred during the Mesozoic era is evidenced by changes in the physiology, behaviour, and morphology of mammals from their reptilian like ancestors.
Therefore, the correct answer option is A.