You are called to attend to an ER patient complaining of sho…

You are called to attend to an ER patient complaining of shortness of breath and severe dyspnea on exertion. Patient history is significant for a 30 year-pack smoking history, dry non-productive cough and occasional pedal edema. CXR findings are not remarkable except for mild cardiomegaly. You want to rule out ILD vs. obstructive lung disease. Which of the following tests may help you to differentiate the diagnosis on this patient?I. sputum culture and sensitivityII. high resolution CTIII. pulmonary function testingIV. arterial blood gas analysisV. PET scan