The round pea seed trait is dominant over the wrinkled pea seed trait. if the phenotype of the pea seed is wrinkled, which combination of genes must have it?
a.)two round genes
b.)one wrinkled gene only
c.)once round gene only
d.)two wrinkled genes

D. It must have two wrinkled genes.
Whenever one or more of the parents' genes are dominant, the resulting daughter gene will be dominant.
Thus, in order to produce a recessive gene, BOTH parent genes must be recessive as well. Because wrinkled genes are recessive, you're going to need both wrinkled genes.