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: Physiology
[{'content': 'O2 consumption is minimal when temp. gradient between skin and external environment is: \nSelect and explain. \nA. < 0.50deg, B. < 2.50deg, C. < 1.50deg, D. > 3.5deg', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A < 0.5degC (still searching)', 'role': 'assistant'}]