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
Oral retinoid is indicated in the treatment of: 
Select and explain. 
A. Acne vulgaris, B. Pemphigus vulgaris, C. Lupus vulgaris, D. Erythema multiforme
A: Acne vulgaris
Answer: A: Acne vulgaris 
Explanation: Acne vulgaris