biochem - explanation

[ArchivalUser]

A 10 yrs pt with light blond hair, pale skin, and significant mental retardation (IQ of 50) is most likely to have a defect at which biochemical pathway? Given the following interconnected pathways. Please choose only to one product and one substrate. For example: tyrosine> dopa (tyrosine becomes dopa)

Phenylalanine > tyrosine>dopa > melanin
Tyrosine>T4
Tyrosine>homogentisic acid>acetoacetic acid

[ArchivalUser]

phenyalanine hydroxylase.
So ans is A

[ArchivalUser]

Read the question carefully your answer include 3 options

[ArchivalUser]

so its phenylalanine>tyrosine

[ArchivalUser]

yes