Cystic fibrosis, which is usually lethal before the age of reproduction, is a homozygous recessive trait. Why do cases continue to arise, even though people with the disease rarely live to reproduce?
a) because new mutations continually introduce this harmful condition into the population
b) because the harmful allele "hides" within heterozygous individuals, one-fourth of the offspring of two heterozygotes would be afflicted.
c) because mosquitoes can transfer the disease from person to person
d) because people continue to make inappropriate lifestyle choices
e) none of the above