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
30 years old male presents with painful flaccid bullae on right face and oral mucosa without evidence of inflammation or redness; what is the most probable diagnosis? 
Select and explain. 
A. Pemphigus vulgaris, B. Pemphigus foliaceous, C. Bullous pemphoid, D. Dermatitis herpetiformis
A: Pemphigus vulgaris
Answer: A: Pemphigus vulgaris 
Explanation: Ans. is 'a' i.e., Pemphigus vulgaris