Question: A 16-year-old boy presents with a chronic cough and shortness of breath. His medical history is significant for recurrent episodes of respiratory tract infections since he was a child and diarrhea that is worse when he eats fried and fatty food. Vital signs are normal. Physical examination demonstrates digital clubbing, coarse crackles in both upper lung zones with occasional bronchial sounds, and a soft abdomen. Laboratory tests show a random blood glucose of 300 mg/dL. A chest x-ray shows features of bilateral bronchiectasis. Which of the following is used as a screening test for this patient's suspected condition? Need Assignment Help service? A. Hgb A1C B. CT thorax C. Hida scan D. Sweat chloride test