This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'In humans and other primates, as well as in guinea pigs, this vitamin cannot be synthesized, because of the absence of the enzyme L-gulonolactone oxidase; the vitamin is: \nSelect and explain. \nA. Pantothenic acid, B. Nicotinic acid, C. Ascorbic acid, D. Folic acid', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]