question: Q:A 68-year-old man presents to the physician with fever, cough, weakness, night sweats, and poor appetite for the past 6 months. Medical records suggest that he has lost 7.5 kg (16.5 lb) of weight during this period. There is no history of breathlessness, nasal discharge, nasal obstruction, palpitations, chest pain, or symptoms related to digestion. He was released from prison 9 months ago after serving a 2-year sentence. His temperature is 38.1°C (100.6°F), pulse is 84/min, respirations are 16/min, and blood pressure is 122/80 mm Hg. Physical examination shows hepatomegaly and generalized lymphadenopathy, and auscultation of the chest reveals diffuse crackles throughout the lung fields bilaterally. On direct ophthalmoscopy, three discrete, yellow-colored, 0.5 mm to 1.0 mm lesions with indistinct borders are seen in the posterior pole. A chest X-ray is shown in the image. Tuberculin skin test with purified protein derivative is negative. What is the most likely diagnosis?? 
  {'A': 'Sarcoidosis', 'B': 'Chronic histoplasmosis', 'C': 'Langerhans cell histiocytosis', 'D': 'Tuberculosis', 'E': 'Bronchoalveolar carcinoma'},