<s>[INST] context: Bronchiectasis:
The most common clinical presentation is a persistent productive cough with ongoing production of thick, tenacious sputum. Physical findings often include crackles and wheezing on lung auscultation, and some patients with bronchiectasis exhibit clubbing of the digits. Mild to moderate airflow obstruction is often detected on pulmonary function tests, overlapping with that seen at presentation with other conditions, such as chronic obstructive pulmonary disease (COPD). 
The diagnosis is usually based on presentation with a persistent chronic cough and sputum production accompanied by consistent radiographic features. Although chest radiographs lack sensitivity, the presence of “tram tracks” indicating dilated airways is consistent with bronchiectasis. Chest CT is more specific for bronchiectasis and is the imaging modality of choice for confirming the diagnosis. CT findings include airway dilation (detected as parallel “tram  tracks” or as the “signet-ring sign”) — a cross-sectional area of the airway with a diameter at least 1.5 times that of the adjacent vessel), lack of bronchial tapering (including the presence of tubular structures within 1 cm from the pleural surface), bronchial wall thickening in dilated airways, inspissated secretions (e.g., the “tree-in-bud” pattern), or  cysts emanating from the bronchial wall (especially pronounced in cystic bronchiectasis). [/INST] question: A patient presents with haemoptysis, copious sputum and tram lines (abnormal air bronchogram) pattern on the chest X ray. What is the most likely diagnosis? | options: A: Lung abscess B: Pulmonary embolism with infarction C: Bronchiectasis D: Carcinoma of lung | answer: C </s>