Answer:
B. 0.42
Explanation:
Since the two alleles are at Hardy-Weinberg equilibrium, the sum of the frequency of two alleles will be one. If the frequency of a dominant allele is "p" and that of the recessive allele is "q", then p+q=1
According to the given information, the frequency of one allele in the population is= 0.7
This means that the frequency of the other allele would be= 1-0.7 = 0.3
Frequency of heterozygote in the population =2pq = 2 x 0.7 x 0.3 = 0.42
