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': 'CAP in Lac operon is an example of: \nSelect and explain. \nA. Positive regulator, B. Negative regulator, C. Constitutive expression, D. Attenuation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Positive regulator', 'role': 'assistant'}]