The Research Conducted on Alcoholism in Identical and Fraternal Twins

The research conducted on alcoholism in identical and fraternal twins has found that

A) there was no difference between identical and fraternal twins in the age at which they began drinking, how much they drank, and whether or not they became problem drinkers.
B) there was no difference between identical and fraternal twins in the age at which they began drinking, but identical twins were more similar in the amount they drank and the risk of becoming a problem drinker.
C) identical twins began drinking on average at a younger age than fraternal twins, but there was no difference between identical and fraternal twins in the amount they eventually drank or their risk of becoming problem drinkers.
D) identical twins began drinking at a younger age than fraternal twins, drank more and were more likely to eventually develop a problem with drinking.