Microevolution is the changes in allele frequencies that occur over time within a population. This change is due to four different processes which are presented below:
 
  The five agents of microevolution are:
  Mutations
  Gene Flow
  Genetic Drift
  Sexual Selection
  Natural Selection
 
  The correct answer choice is: A) It is a change in allele frequency within a population.
 
  I hope this helps, Regards.