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': 'Severe HTN cut off is \nSelect and explain. \nA. >140 mm Hg, B. >150 mm Hg, C. >160 mm Hg, D. >170 mm Hg', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. D >170 mm HgRef: Harrison's, 19th ed. pg. 1616Guidelines for threshold values between normal and high blood pressure Clinic measurement (mm Hg)Home measurement (mm Hg)Optimal control<140/85<130/80Mild hypertension140-150/90-100135-145/85-95Moderate hypertension150-170/100-110145-165/95-105Severe hypertension>170/110>165/105The question mentioned was severe hypertension, however if the grading of hypertension is asked, then answer must be according to this table:BP classificationSystolic mm HgDiastolic, mm HgNormal<120and <80Pre-hypertension120-129<80Stage 1 HTN130-13980-89Stage II HTN>140>90Isolated systolic HTN>140and <90", 'role': 'assistant'}]