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
Randomisation is useful to eliminate:(1994) 
Select and explain. 
A. Observer bias, B. Confounding factors, C. Patient bias, D. Sampling bias
B: Confounding factors
Answer: B: Confounding factors 
Explanation: Ans: bRef: Park, 17th ed, p. 72 & 18th ed, p. 76