a plant has 4 genes a, b, c and d on chromosome 5. gene a is very tightly linked to b and gene c is very tightly linked to d. a plant homozygous for alleles a, b, c and d is crossed with another plant homozygous for alleles a, b, c and d. what should be the approximate predicted phenotypic ratio of the f2 population?
a. 9:3:3:1
b. 27:9:9:9:3:3:3
c. 1:2:2:4:1:2:1:2:1
d. 1:1:1:1