A series of experiments shows that oil content in a diploid grain is influenced by five genes (a through e) with additive alleles. Each gene contributes an equal amount to the oil content. The highest producing strain is 20% oil content; the lowest has close to 0%. A plant of unknown genotype has an oil content of 12%. What is a possible genotype for this plant? (+ = additive alleles)

a. a+a+b+b+c+c+d+de+e

b. a+a+b+b+ ccddee

c. a+a+bbccddee

d. aab+bc+cd+d+e+e+

e. aab+bccdd+ee+