If the two characteristics that Mendel looked at in his dihybrid cross of smooth yellow peas with wrinkled green peas had been controlled by genes that were located close together on the same chromosome, then the F2 generation .

a) would have contained four phenotypes in a 9:3:3:1 ratio
b) would have contained only individuals that were heterozygous at both loci
c) would have deviated from the 9:3:3:1 phenotypic ratio
d) would have contained no individuals that were heterozygous at both loci