The correct answer is B. Desmoglein.

The image shows umbilicated papules consistent with molluscum contagiosum. Treatment of molluscum contagiosum involves cantharidin, which disrupts desmosomes and leads to acantholysis. Desmoglein is the only protein listed that is a main component of desmosomes.

Cadherin is a part of the adherens junction, while plectin is a component of the hemidesmosome; neither of these options are linked to cantharidin-associated acantholysis. Inhibition of RNA polymerase is the mechanism of rifampin, which is not the appropriate medication for molluscum contagiosum. Tubulin is bound by popdophyllin, which leads to antimitotic activity in genital warts.

References:

Al-Dawsari NA, Masterpol KS. Cantharidin in Dermatology. Skinmed. 2016;14(2):111-114. Published 2016 Apr 1.