If a boy exhibits a sex-linked trait that is carried on the X chromosome, what must be true?
AHis mother exhibited that trait.
BHis father exhibited that trait.
CHis father’s mother carried an allele for that trait.
DHis mother carried at least one allele for that trait.
AHis mother exhibited that trait.
BHis father exhibited that trait.
CHis father’s mother carried an allele for that trait.
DHis mother carried at least one allele for that trait.