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
Non - sampling errors may occur due to all the following except- 
Select and explain. 
A. Inadequately calibrated instruments, B. Repeated sampling, C. Observer variation, D. Conceptual errors
B: Repeated sampling
Answer: B: Repeated sampling 
Explanation: Errors may occur not only due to error in sample survey but also due to inadequately calibrated instruments, observer variation, incomplete coverage, and conceptual errors. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 913