Sure, let's find the frequency of the `rr` genotype in this plant population step-by-step.
1. Count the Total Number of Individuals:
The number of individuals for each genotype is as follows:
- RR: 20 individuals
- Rr: 50 individuals
- rr: 30 individuals
To find the total number of individuals, we sum these up:
[tex]\[
\text{Total individuals} = 20 + 50 + 30 = 100
\][/tex]
2. Calculate the Frequency of the rr Genotype:
The frequency of a genotype is the number of individuals of that genotype divided by the total number of individuals.
[tex]\[
\text{Frequency of } rr = \frac{\text{Number of rr individuals}}{\text{Total number of individuals}} = \frac{30}{100} = 0.3
\][/tex]
3. Determine the Closest Answer Choice:
Comparing our calculated frequency to the provided choices:
- A. 0.5
- B. 1.0
- C. 0.2
- D. 0.3
We see that the frequency of 0.3 matches choice D.
So, the frequency of the rr genotype is [tex]\( \boxed{0.3} \)[/tex]. The correct answer is D.