Because individuals with cystic fibrosis die before they can reproduce, the coefficient of selection against them is s = 1. Assume that heterozygous carriers of the recessive mutant allele responsible for this disease are as fit as wild-type homozygotes and that the population frequency of the mutant allele is 0.02.

(a) Predict the incidence of cystic fibrosis in the population after one generation of selection. 

(b) Explain why the incidence of cystic fibrosis hardly changes even with s = 1.