Understanding Autosomal and Sex-Linked Inheritance Practice Test

Scientists have characterized a new genetic disorder that only affects males. What is the most likely explanation of how this disorder is passed from generation to generation?

Color blindness is determined by a sex-linked recessive allele found on the X chromosome. A family has a daughter that sees normally, but a son that is color blind. The mother and father both have normal vision. The maternal grandfather also has normal vision.

Based on this family history, which statement is true?