You are answering a USMLE-style medical question. Question: A 23-year-old man comes to the clinic for yellowing of his eyes. The patient has been relatively healthy and just recently started “intermittent fasting” to try to lose weight. He recalls a similar episode 4 years ago when he was recovering from an emergency appendectomy. The patient denies smoking but endorses an episode of binge drinking 2 days ago. He is sexually active with both men and women. His physical examination is unremarkable besides scleral icterus. What is the most likely explanation for this patient’s symptoms? Options: A) Autoimmune-mediated fibrosis of biliary tract B) Chronic viral infection of the liver C) Decreased activity of UDP-glucuronosyltransferase D) Defective bilirubin excretion Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.