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
Recalcitrant Pustular Acne is treated by 
Select and explain. 
A. Oral Erythromycin, B. Oral tetracycline, C. Steriod, D. Retinoid
D: Retinoid
Answer: D: Retinoid 
Explanation: D i.e. Retonoid