Newborn Screening Reveals That Newborn Jessica Has Inherited PKU

Newborn screening reveals that newborn Jessica has inherited PKU.Her parents are distraught at the diagnosis,but a nutritionist explains that Jessica can be treated,right away.The treatment for PKU is

A) nonheritable gene therapy.
B) heritable gene therapy.
C) exchange of her blood supply.
D) twice daily respiratory therapy, performed by the parents.
E) dietary.