You are answering a USMLE-style medical question. Question: A 77-year-old man comes to your office for a routine visit. He is doing well, and his only complaint is the recent appearance of several brown greasy appearing lesions on his forehead (figure A) that he can't seem to peel off. What is the most likely diagnosis? Options: A) Melanoma B) Seborrheic keratosis C) Acanthosis nigricans D) Erythema nodosum Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.