What Is the Most Likely Explanation for the Light Skin

Multiple Choice

What is the most likely explanation for the light skin and hair of people with PKU?

A) Too much phenylalanine interferes with the production of melanin.
B) Their expression levels of the genes that produce melanin are low.
C) They cannot adequately synthesize tyrosine, an important precursor of melanin.
D) Melanin is broken down by excess phenylalanine.
E) Phenylalanine interferes with the transport of melanin to the appropriate location.