<prompt> Ferric chloride test is used to diagnose:PhenylketonuriaAlkaptonuriaHartnup diseaseCystinuria  <response>: a. PheylketonuriaRef: Nelsons 20e p 636-642; Ghai 8e p 653-655Ferric chloride test is used to determine the presence or absence of phenols in a given sample.FeCl3 test with urine gives green colour in Phenylketonuria detects phenylalanine in urine. 