a horticulturalist wants to produce geraniums with specific characteristics. she knows that the trait of red flowers is governed by the allele r(rr and rr) and the trait of white flowers is governed by the allele r(rr). the horticulturalist plans to cross a geranium that is true-breeding for red flowers with a geranium that is true-breeding for white flowers. which punnett square best describes this cross?