This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'Normal QRS axis \nSelect and explain. \nA. +30 to 110deg, B. -30 to 110deg, C. +110deg to +150deg, D. - 110deg to - 150deg', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) -30 to 110degRef: Ganong, 25th ed/p.524Normally, the QRS axis ranges from -30deg to +100degAxis more negative than -30deg is called left axis deviationAxis more positive than +100deg is called right axis deviation', 'role': 'assistant'}]