**Core Concept**
The patient presents with a characteristic skin manifestation, bullae, over the trunk and back. This clinical presentation is suggestive of a specific autoimmune blistering disorder. The absence of systemic symptoms, normal oral mucosa, and lack of other skin involvement point towards a localized disease process.

**Why the Correct Answer is Right**
The clinical presentation is consistent with Pemphigus Vulgaris (PV), an autoimmune disease characterized by the formation of autoantibodies against desmoglein 3 proteins, which are crucial for epidermal cell-to-cell adhesion. The autoantibodies lead to the breakdown of these adhesion molecules, resulting in the formation of intraepidermal blisters. The absence of mucosal involvement and the presence of bullae are key distinguishing features of PV from other autoimmune blistering disorders like Pemphigus Foliaceus.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be tempting, but it is incorrect because Pemphigus Vulgaris typically involves the mucous membranes, especially the oral cavity, which is not the case in this patient.

**Option B:** This option is incorrect because Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are severe skin conditions often associated with medication use or infections, which does not fit this patient's presentation.

**Option C:** This option is incorrect because Bullous Pemphigoid is an autoimmune blistering disorder that typically involves the elderly and presents with tense blisters, often on the lower extremities and trunk, but it is less likely to involve the oral mucosa.

**Option D:** This option is incorrect because Staphylococcal Scalded Skin Syndrome is a condition caused by staphylococcal toxins that typically affects infants and young children, leading to widespread blistering and peeling of the skin.

**Clinical Pearl / High-Yield Fact**
Pemphigus Vulgaris is a classic example of an autoimmune disease that can masquerade as a dermatological condition, highlighting the importance of considering systemic causes for skin manifestations, even in the absence of systemic symptoms.

**Correct Answer: C. Perform a biopsy of the unroofed blister to demonstrate the characteristic intraepidermal acantholysis with suprabasal clefting and a band-like inflammatory infiltrate.**