Which of the following is true regarding biology and alcohol use?

Which of the following is true regarding biology and alcohol use?
 
  a. Genes related to the bodys ability to break down alcohol in the liver are distributed evenly across the worlds populations.
  b. Native Americans have much higher rates of alcohol dependence than many other ethnic groups in the United States because they lack protective genes.
  c. Certain types of genes found primarily in Europeans are correlated with higher rates of alcohol tolerance.
  d. Certain types of genes found primarily in Asians are correlated with lower rates of alcohol dependence.