assume that three loci, each with two alleles (A/a, B/b, and D/d), determine the differences in height between two homozygous varieties of a plant. These genes are addictive (A,B,D) and contribute equally to plant height. One variety (aa bb dd) is 20 cm in height, while the other strain (AA BB DD) is 38cm in height. The two strans are crossed, and the resulting F1 are inter-crossed to produce F2 progeny.

(a) How tall are the F1 plants?
(b) IN the F2, what fraction of the plants will be 20cm in height?
(c) HOw much does each additive allele-contribute to plant height?