Frequency of heterozygotes in the population is 0.4. 
C. 0.4
Step-by-step explanation:
If a population is in Hardy-Weinberg equilibrium, the sum of the frequencies of the two alleles will be equal to 1. The letter p denotes the frequency of the first allele and the letter q denotes the frequency of the second allele. 
p+q=1 
In the problem it is given that p=0.6 
p+q=1 
0.6+q =1 
q= 1-0.6
=0.4 
We have to calculate the frequency of heterozygotes in the population. it is given by the equation 
Number of heterozygous individuals =2pq 
=

=0.48~0.4