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: Skin
Treatment of nodulocystic acne ? 
Select and explain. 
A. Erythromycin, B. Isoretinonine, C. Tetracycline, D. Steroids
B: Isoretinonine
Answer: B: Isoretinonine 
Explanation: Ans. is 'b' i.e., Isoretinonine