a) Both parent plants are heterozygous for a dominant allele that causes the red colour. The dominant allele is for red flowers (R) and the recessive allele is for white flowers (r), hence the genotype of the parents is Rr. b) Trait 'r' is the recessive trait, whereas trait 'R' is the dominant trait. c) This cross is known as a monohybrid cross because it involves one gene locus, locus for color.  Every offspring with a R will have the color red and without R will be white.  As a result, the chance is that 75 percent will be red and 25 percent will be white. That is, for every four children, three will be red and one will be white. This results in a 75:25 = 3:1 ratio.