Achondroplasia Is a Form of Dwarfism That Is Inherited in Humans

Achondroplasia is a form of dwarfism that is inherited in humans as an autosomal dominant.A survey in a small country showed that, within a 2-year period, there were 12 children with normal parents born with this disorder out of a total of 420, 000 births.What is the mutation rate in mutations/locus/generation?

A) 1) 4 × 10^-5
B) 2) 8 × 10^-6
C) 2) 5 × 10^-5
D) 2) 8 × 10^-5
E) 7) 4 × 10^-6