This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
Enzyme-deficient in Alkaptonuria 
Select and explain. 
A. Phenylalanine hydroxylase, B. Cystathionine synthase, C. Homogentisic acid oxidase, D. Tyrosinase
C: Homogentisic acid oxidase
Answer: C: Homogentisic acid oxidase 
Explanation: .