In sweet pea gene C or P alone produces white flower, where as both C and P are needed to produce purple coloured flower. In a particular cross between two white flowered plants the offsprings were one half purple and one-half white. The possible genotypes of the parents is

In the sweet peas gene, C or P alone produces a white flower, whereas both C and P are needed to produce a purple-colored flower. In a particular cross between two white-flowered plants, the offspring were one-half purple and one-half white. The possible genotypes of the parents are ccPp × CCpp.
As offspring are both purple and white therefore both the genes C and P must be in the heterozygous condition in parents either dominant or recessive form.