At the supermarket you typically find three types of onions: red, yellow, and white. when true breeding plants with red onions were crossed to true breeding plants with white onions, all the f1 plants had white onions. in the f2 progeny there were 980 plants with white onions, 250 plants with red onions and 80 plants with yellow onions. how many genes are involved in determination of color in onions?

2 genes.

Explanation:

In F1 there are two genes involved in the determination of color, the gene that codifies for white onions and the gene that codifies for red onions, the white gene was the dominant gene giving all white onions. F2 progeny has white, red and yellow onions. That means that in the case of yellow onions there is a codominance between the red and white gene because both of them were expressed giving 80 yellow onions. In the case of the 250 red onions the dominant gene is the red one and the withe is recessive. Finally for the 980 white onions the white gene is the dominant one and the red one is the recessive.

the answer is c because it is most logical.