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
Which among the following is TRUE about confounding factor? 
Select and explain. 
A. It is found equally between study and the control groups, B. It is itself 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 is itself a risk factor for the disease
Answer: B: It is itself a risk factor for the disease 
Explanation: A confounding factor is defined as one which is associated both with exposure and disease, and is distributed unequally in study and control groups. More specifically a confounding factor is one that, although associated with exposure under investigation, is itself, independently of any such association, a risk factor for the disease. Ref: Park's Textbook of Preventive and Social Medicine, 19th edition, Page 67.