You are answering a USMLE-style medical question. Question: A 59-year-old man presents to his primary care provider with fatigue, a progressively worsening cough with flecks of blood, shortness of breath, and dark urine. He reports feeling ill for the past 3 weeks. Past medical history is significant for hypertension and hyperlipidemia. He takes chlorthalidone and atorvastatin. Family history is noncontributory. He has smoked 20–30 cigarettes daily for the past 26 years. Anti-glomerular basement membrane serologies are positive. Which of the following is a specific feature for this patient’s condition? Options: A) Granulomatous inflammation and necrotizing vasculitis B) Positive cryoglobulins C) Linear IgG staining on immunofluorescence D) Longitudinal splitting and thickening of the glomerular basement membrane Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.