C. Two plants, both heterozygous for the gene that controls flower color are crossed. What percentage of their offspring will have purple flowers? __ White Flowers? __

## Step 1
The problem involves the principles of genetics, specifically the concept of incomplete dominance. Incomplete dominance is a form of inheritance where the phenotype of the heterozygous genotype is an intermediate phenotype between the two homozygous phenotypes.

## Step 2
In this problem, we are given that both plants are heterozygous for the gene that controls flower color. This means that each plant has two different alleles for the flower color gene, one for purple flowers and one for white flowers.

## Step 3
When these plants are crossed, the possible combinations of alleles in the offspring are: purple-purple, purple-white, white-purple, and white-white.

## Step 4
The purple-purple and purple-white combinations will result in purple flowers, while the white-purple and white-white combinations will result in white flowers.

## Step 5
The ratio of these combinations is 1:2:1, which means that 1/4 of the offspring will have purple flowers, 1/2 will have purple-white flowers (which will also have purple flowers), and 1/4 will have white flowers.

## Step 6
Therefore, the percentage of offspring with purple flowers is 75% (1/4 + 1/2), and the percentage of offspring with white flowers is 25% (1/4).