The problem asks us to determine the potential genotypes of the parent plants given a partial Punnett square. The Punnett square shows two offspring with the genotype $Rr$. We need to figure out which parental genotypes could produce offspring with $Rr$ in the Punnett square.

1. Problem Description

The problem asks us to determine the potential genotypes of the parent plants given a partial Punnett square. The Punnett square shows two offspring with the genotype $Rr$. We need to figure out which parental genotypes could produce offspring with $Rr$ in the Punnett square.

2. Solution Steps

We will analyze each of the given options.

A) $RR \times Rr$:

The possible offspring genotypes are $RR$, $RR$, $Rr$, and $Rr$. This cross will produce offspring with $Rr$.

B) $RR \times rr$:

The possible offspring genotypes are $Rr$, $Rr$, $Rr$, and $Rr$. This cross will produce offspring with $Rr$.

C) $Rr \times rr$:

The possible offspring genotypes are $Rr$, $Rr$, $rr$, and $rr$. This cross will produce offspring with $Rr$.

D) $rr \times rr$:

The possible offspring genotypes are $rr$, $rr$, $rr$, and $rr$. This cross will not produce offspring with $Rr$.

From the given partial Punnett square, we only know that the offspring can be $Rr$. From the options:

A) $RR \times Rr$: This cross can produce offspring $Rr$. But can also produce $RR$.

B) $RR \times rr$: This cross only produces $Rr$ offspring. Therefore only $Rr$ can be in the partial Punnett square. However, the question asks for potential genotypes, therefore this option would not make sense.

C) $Rr \times rr$: This cross can produce $Rr$ and $rr$ offspring.

D) $rr \times rr$: This cross only produces $rr$ offspring, so this can't be it.

Looking at the given options and the partial Punnett square, option C ($Rr \times rr$) is the most likely parental genotype since the offspring $Rr$ can be produced. The other option that produces offspring $Rr$ is $RR \times rr$.

Since the question specifies a PARTIAL Punnett square showing offspring genotypes, we are looking for parental genotypes whose crosses yield offspring $Rr$. Therefore, cross C is the answer. If we did cross A the square may yield $RR$ but this isn't shown here so it cannot be a correct answer.

3. Final Answer

C) Rr x rr