Farmer`s lung:- caused by Thermophilic Actinomycetes it is occupational disease - So, no seasonal predilection occur in Asthma - Hypersensitivity pneumonitis occurs due to inhalational exposure to variety of antigens leading to inflammatory response of alveoli and small airways. Choice A is ruled out as asthma attacks are seasonal in nature. Choice B is ruled out as major complaint of the patient in Hypersensitivity Pneumonitis is dyspnea associated with fever, chills and malaise. Choice D is ruled out as alveoli are involved in HP. The answer by exclusion is choice C. Causes of Upper lobe involvement of lungs Inhaled injurious gases Smoke inhalation Centrilobular emphysema Impaired mucociliary clearance Cystic fibrosis Inhaled paiculates: pneumoconiosis Silicosis Coal worker pneumoconiosis Berylliosis Miscellaneous pneumoconiosis (hard metal disease, kaolinosis, bauxite pneumoconiosis, fuller eah disease) Inhaled antigens Hypersensitivity pneumonitis Allergic bronchopulmonary aspergillosis Chronic eosinophilic pneumonia Granulomatous disease Granulomatous disease Tuberculosis Sarcoidosis Langerhans Cell histiocytosis Broncho centric granulomatous Abnormal perfusion kinetics Right-sided localized pulmonary edema in acute mitral regurgitation Neurogenic pulmonary edema Metabolic disease Metastatic pulmonary calcification Increased mechanical stress Ankylosing spondylitis