The allele for cystic fibrosis is recessive. What does this mean?
A.
The allele for cystic fibrosis is only passed along when a person carrying it is homozygous for it.
B.
Cystic fibrosis will kill any person with that allele.
C.
Cystic fibrosis never affects anyone with the allele--it is only carried.
D.
Cystic fibrosis can be carried in a heterozygote and kill a homozygous offspring.