Answer:
Option D ,

Step-by-step explanation:
Given -
Frequency of individuals that are resistant (rr) is
represented as "
"
Frequency of individual that are not resistant with homozygous dominant genotype (RR) is
represented as "
"
Frequency of individual that are not resistant with heterozygous (Rr) genotype is
represented as "
"
As per Hardy Weinberg equation , at equilibrium-

Thus, the given population follow hardy Weinberg equilibrium.
Thus, frequency of the r allele in the population is equal to

The nearest value to this frequency is option D
Hence option D is correct.