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
A 24 years old (middle aged) female has flaccid bullae in the skin and persistent painful oral erosions (palatal & vestibular lesions in buccal mucosa). Histopathology shows intraepidermal acantholytic blister. The most likely diagnosis is 
Select and explain. 
A. Bullous Pemphigoid., B. Erythema multiforme, C. Pemphigus vulgaris., D. Dermatitis herpetiformis.
C: Pemphigus vulgaris.
Answer: C: Pemphigus vulgaris. 
Explanation: C i.e. Pemphigus vulgaris