This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': "On 1st day, patient's BP is measured by a doctor, which is 130/80 mm of Hg. After 3 days, pt is again brought to the hospital while another doctor is on duty. Pt is under same physical & emotional state as 3 days ago. Now B.P is measured which is 150/97. Which of the following explains this reading ? \nSelect and explain. \nA. Leaking of valve, that donot completely encircle the arm., B. Due to fear of the patient., C. Due to observer error., D. Due to instrumental error.", 'role': 'user'}, {'content': "Answer: C \nExplanation: 3 errors are normally seen in measuring B.P: 1. Subject errors : Reading is disturbed d/t fear/any emotional stress of the patient. 2. Observer errors : Due to difference in interpreting koratkoff's sounds & hearing power of different doctors 3. Instrumental error : Due to any problem in B.P apparatus resulting in false reading. - In the given question, as patient's physical & emotional state is the same, subject bias is unlikely to occur - As two doctors took the reading at two different times, it point towards observer error as there would be differences b/w their hearing acuity & interpreting sounds.", 'role': 'assistant'}]