This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vesiculobullous (Blistering) Disorders, Subject name: Skin
70-year-old female came with multiple erosion & flaccid bulla over skin. Slight rubbing of the skin results in exfoliation of the outermost layer, forming a blister within minutes. Erosions were present over oral mucosa. No target lesion seen. Diagnosis? 
Select and explain. 
A. Pemphigus vulgaris, B. Bullous pemphigoid, C. Dermatitis herpetiformis, D. SJS
A: Pemphigus vulgaris
Answer: A: Pemphigus vulgaris 
Explanation: Ans. a. Pemphigus vulgarisMucosal involvement, nikolsky sign (exfoliation of skin on rubbing) positive, flaccid bulla with erosions - all are features of pemphigus vulgaris.Target lesions are seen in erythema multiformeMucosal involvement is absent in bullous pemphogoid.