This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Pathology, Subject name: Pathology
[{'content': 'So the following heme degradation products in order of production: a. Protoporphyrin b. Urobillinogen c. Bilirubin d. Biliverdin \nSelect and explain. \nA. a,c,d,b, B. b,d,c,a, C. a,d,c,b, D. b,c,d,a', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]