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: Pharmacology
Which teratogen causes deafness ? 
Select and explain. 
A. Isotretnoin, B. Chloroquine, C. Alcohol, D. Warfarin
A: Isotretnoin
Answer: A: Isotretnoin 
Explanation: Ans. is 'a' i.e., Isotretnoid o Isotretinoin can cause microtia or anotia. o These defects are frequently associated with agenesis or stenosis of external ear canal and may lead to deafness.