Given three possible phenotypes for parents showing dominance (aa, aa, aa), which combination would produce a 1: 2: 1 ratio of genotypes and a 3: 1 ratio of phenotypes?
i. aa x aa
ii. aa x aa
iii. heterozygous x heterozygous
iv. aa x aa
v. homozygous dominant x heterozygous
a) i, ii, iii, iv, and v only
b) iii and iv only
c) i and v only
d) ii only