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
Which of the following types of bias can be reduced by by allowing equal interview time- 
Select and explain. 
A. Berkesonian bias, B. Recall bias, C. Selection bias, D. Interviewer bias
D: Interviewer bias
Answer: D: Interviewer bias 
Explanation: Interviewer's bias Occur when interviewer knows the hypothesis and know who the cases are. This type of bias can be eliminated by double-blinding. (refer pgno:74 park 23 rd edition)