Fruit flies homozygous for the recessive mutation scarlet have bright red eyes because they cannot synthesize brown pigment. Fruit flies homozygous for the recessive mutation brown have brownish-purple eyes because they cannot synthesize red pigment. Fruit flies homozygous for both of these mutations have white eyes because they cannot synthesize either type of pigment. The brown and scarlet mutations assort independently. If fruit flies that are heterozygous for both of these mutations are intercrossed, what kinds of progeny will they produce, and in what proportions?