The following are multiple choice questions (with answers) about medical knowledge.   **Question:** A 65-year-old male presents to his pulmonologist for a follow-up visit. He has a history of chronic progressive dyspnea over the past five years. He uses oxygen at home and was seen in the emergency room two months prior for an exacerbation of his dyspnea. He was discharged following stabilization. His past medical history is notable for hyperlipidemia and hypertension. He drinks alcohol socially and has a 45 pack-year smoking history. His temperature is 98.6°F (37°C), blood pressure is 140/75 mmHg, pulse is 110/min, and respirations are 22/min. On examination, increased work of breathing is noted. The physician decides to start the patient on an additional medication that has both mucoactive and anti-oxidative properties. What is the primary mechanism of action of this medication in the lungs?   (A) DNA hydrolysis   (B) Disulfide bond cleavage   (C) Endothelin-1 antagonism   (D) Reduction in airway surface tension
['(B) Disulfide bond cleavage <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) DNA hydrolysis \n (B) Disulfide bond cleavage \n (C) Endothelin-1 antagonism \n (D) Reduction in airway surface tension <> possible answers', '  A 65-year-old male presents to his pulmonologist for a follow-up visit. He has a history of chronic progressive dyspnea over the past five years. He uses oxygen at home and was seen in the emergency room two months prior for an exacerbation of his dyspnea. He was discharged following stabilization. His past medical history is notable for hyperlipidemia and hypertension. He drinks alcohol socially and has a 45 pack-year smoking history. His temperature is 98.6°F (37°C), blood pressure is 140/75 mmHg, pulse is 110/min, and respirations are 22/min. On examination, increased work of breathing is noted. The physician decides to start the patient on an additional medication that has both mucoactive and anti-oxidative properties. What is the primary mechanism of action of this medication in the lungs? <> context@']