You are answering a USMLE-style medical question. Question: A 62-year-old woman with small-cell lung cancer comes to the physician because of a painful, burning red rash on her face and hands that developed 30 minutes after going outside to do garden work. She wore a long-sleeved shirt and was exposed to direct sunlight for about 10 minutes. The patient is light-skinned and has a history of occasional sunburns when she does not apply sunscreen. Current medications include demeclocycline for malignancy-associated hyponatremia and amoxicillin for sinusitis. Physical examination shows prominent erythema and a papular eruption on her forehead, cheeks, neck, and the dorsum of both hands. Which of the following is the most likely cause of this patient's symptoms? Options: A) Degranulation of presensitized mast cells B) Formation of drug-induced autoantibodies C) Accumulation of porphobilinogen D) Cell injury due to drug metabolites Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.