a dark-red strain and a white strain of wheat are crossed and produce an intermediate, medium-red f1. when the f1 plants are interbred, and f2 generation is produced in a ratio of 1 dark-red: 20 medium-dark-red: 22 medium-red: 20 light-red: 1 white. further crosses reveal that the dark-red and white f2 plants are true breeding. how many genes are involved in the production of color? group of answer choices