B is the correct answer

A skin biopsy with direct immunofluorescence staining is the gold standard for the diagnosis of pemphigoid gestationis. Linear complement C3 deposition at the basement membrane is pathognomonic for this disease. Diagnosis can be suspected based on physical exam findings including urticarial papules and plaques with tense blisters that begins periumbilically. Serum antibody assays can also be helpful in the diagnosis. Pemphigoid gestationis is an autoimmune condition that is more common with a patient’s first pregnancy and has a high rate of recurrence. It classically will present earlier with more severe symptoms in subsequent pregnancies. Treatment goals are to relieve pruritus and minimize blister development. High-potency topical corticosteroids are recommended for initial treatment. Systemic corticosteroids may be used if topical treatment alone is ineffective. Pemphigoid gestationis is associated with small-for-gestational-age infants and preterm delivery, thus increased antenatal surveillance should be considered. As this condition is autoimmune and mediated by IgG antibodies which freely cross the placenta, a small percentage of newborns will manifest similar dermatologic symptoms and findings that are self-limited.

Clinical presentation alone (A) is not sufficient for diagnosis, since it is important to distinguish this condition from pruritic urticarial papules and plaques of pregnancy due to the increase fetal risk with pemphigoid gestationis. Both skin scrapings for herpes, nucleic acid amplification tests (C) and skin scrapings for Tzanck prep (D) are appropriate to evaluate for herpes virus. Despite the previous name for pemphigoid gestationis being herpes gestationis, it has nothing to do with the family of herpes viruses.