A consequence of organelle heredity is that sequence changes in mtDNA vary more than nuclear DNA in ...

A consequence of organelle heredity is that sequence changes in mtDNA vary more than nuclear DNA in response to reduction in population size. Which of the following does this imply about human evolutionary history?
 
  A) Current human populations must have a much higher mutation rate than ancient populations.
  B) Mitochondrial variants in people descending from originally small populations show enough diversity to be used to construct an evolutionary tree.
  C) The original human population must have grown to be quite large before its members began migrating to other lands and other continents.
  D) Nuclear gene sequencing must be used to resolve the question of human ancestral origins.
  E) A single human population, living about 200,000 years ago, could not have given rise to all current human populations.