Mom and Dad Have Two Sons and Two Daughters

Multiple Choice

Mom and Dad have two sons and two daughters. One son is red-green color-blind. What does this tell us about Mom and Dad?

A) Dad must be color-blind, because a son gets that gene from his father.
B) Mom must be color-blind and passed two recessive genes to her son.
C) Dad must be a carrier and passed the gene to his son.
D) Mom must be a carrier and passed the gene to her son.