You are answering a USMLE-style medical question. Question: A 40-year-old man comes to the emergency department with a 4-day history of left leg pain. Over the weekend, he scraped his left thigh when he fell on a muddy field while playing flag football with some friends. Since that time, he has had progressively worsening redness and pain in his left thigh. Past medical history is unremarkable. His temperature is 39.4°C (103.0°F), heart rate is 120/min, and blood pressure is 95/60 mm Hg. Physical exam is significant for a poorly-demarcated area of redness on his left thigh, extending to about a 10 cm radius from a small scrape. This area is extremely tender to palpation, and palpation elicits an unusual 'crunchy' sensation. CT scan shows free air in the soft tissue of the left leg. The organism that is most likely responsible for this patient's presentation is also a common cause of which of the following conditions? Options: A) Bacterial pneumonia B) Bacterial sinusitis C) Food-borne illness D) Urinary tract infection Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.