You are answering a USMLE-style medical question. Question: A 43-year-old woman comes to the physician because of a 1-day history of rash on the trunk and lower extremities. Three days ago, she visited a spa resort with multiple swimming pools and whirlpools. A friend of hers who also visited the spa has developed a similar rash. She does not smoke or drink alcohol and takes no medications. She appears well. Her vital signs are within normal limits. Examination shows multiple erythematous, excoriated papules and pustules over the trunk and upper thighs. The inflammation seen in this patient's condition most likely originated in which of the following parts of the skin? Options: A) Superfical epidermis B) Hair follicles C) Papillary dermis D) Eccrine sweat glands Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.