This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Random error - 
Select and explain. 
A. Systemic error, B. Bias, C. Reduces precision, D. Confounding factor
D: Confounding factor
Answer: D: Confounding factor 
Explanation: Ans. is 'd' i.e., Reduces precision