Question: If an autosomal recessive disorder which shows Hardy-Weinberg equilibrium has an incidence of 1 in 6400 then the frequency of carriers is approximately _______.
A: 1 in 20
B: 1 in 40
C: 1 in 80
D: 1 in 160
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option.