This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'Which of the following is porphyrines gives stools their characteristics brown color? \nSelect and explain. \nA. Biliverdin, B. Urobilinogen, C. Heme, D. Stercobilin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Stercobilin is a tetrapyrrolic bile pigment and is one end-product of heme catabolism. It is the chemical responsible for the brown color of human feces and was originally isolated from feces in 1932Urobilinogen is a colourless by-product of bilirubin reduction.Heme or haem is a cofactor consisting of a Fe2+ (ferrous) ion contained in the centre of a large heterocyclic organic ring called a porphyrin', 'role': 'assistant'}]