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
What is true about confounding factor? 
Select and explain. 
A. It is found equally between study and control groups, B. It itself is a risk factor for the disease, C. Confounding can be eliminated by selecting a small group, D. It is associated with either the exposure or the disease
B: It itself is a risk factor for the disease
Answer: B: It itself is a risk factor for the disease 
Explanation: Confounding factor is defined as one which is associated with both exposure and disease and is distributed unequally in study and control groups. (refer pg no:72 park 23 rd edition)