Answer: Option C
Explanation:
Phenylketonuria is a rare genetic disorder in which an amino acid known as phenylalanine to build up inside the body.
PKU is a disorder in which the there is a defect in the gene which helps in create the enzyme needed to breakdown the phenylalanine.
The level of phenylalanine in the individuals before birth is normal but after birth the concentration of the amino acid phenylalanine is abnormally high because the enzyme is not synthesized in the body that is responsible for its breakdown.