Which statement correctly compares the inheritance of blood type in humans and the inheritance of length of ears in corn plants?

A. Blood type is controlled by multiple forms of a single gene, while the length of corn ears is controlled by many different genes.
B. Blood type is controlled by many different genes, while the length of corn ears is controlled by multiple forms of a single gene.
C. Both blood type and the length of corn ears are controlled by multiple forms of a single gene.
D. Both blood type and the length of corn ears are controlled by many different genes.