The stem is describing bullous pemphigoid, which produces IgG antibodies hemidesmosomes. (PV is IgG antibodies aginst desmoglein-1 and desmoglein-3, in the oral mucosa).
BP produces the tense blisters that have a negative Nikolsky sign (don't rupture with rubbing). This is because they're supepidermal. Surprised they didn't ask about hemidesmosomes, but I think that that the BP antigen is part of the hemidesmosomes and recruits the autoantibodies.