<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 50-year-old man is brought to the emergency department by his wife because of lethargy and confusion for the past 24 hours. He has also had a productive cough for the past year and has had a 10-kg 22-lb weight loss over the past 6 months. He has a history of multiple sclerosis and has not had an acute exacerbation in over 10 years. For the past 30 years, he has smoked 2 packs of cigarettes daily. He drinks 2 beers every day after work. His temperature is 37.0C 98.6F, pulse is 90min, blood pressure is 13090 mm Hg, and respirations are 22min. On examination, the patient appears lethargic and cannot state his name or his location. Physical examination reveals scattered wheezing bilaterally. Deep tendon reflexes cannot be elicited. Laboratory studies show:SerumNa 115 mEqLK 4.5 mEqLHCO3- 22 mEqLGlucose 70 mgdLBlood urea nitrogen 8 mgdLUrine osmolality 450 mOsmolkg H2OUrine sodium 70 mEqLAn x-ray of the chest reveals a central lung mass. Which of the following is the next best step in management?? A: Order CT scan of the chest, B: Administer furosemide, C: Administer hypertonic saline, D: Administer demeclocycline, E: Administer conivaptan,  <response>: This is a clinical vignette describing a 50-year-old man with lethargy, confusion, chronic productive cough, weight loss, smoking history, multiple sclerosis, and findings of hyponatremia and a lung mass on imaging. The key findings here are:- Hyponatremia low sodium - serum Na 115 mEqL- Urine osmolality 450 mOsmolkg H2O - indicates his kidneys are able to concentrate urine, so this is not an issue with his kidneys- Urine sodium 70 mEqL - indicates his kidneys are able to excrete sodium appropriately - Lung mass on x-ray - concerning for malignancy as a cause of his symptomsThe hyponatremia in the setting of likely malignancy suggests this patient has syndrome of inappropriate antidiuretic hormone secretion SIADH. The next best step would be to treat the underlying cause if possible.C: Administer hypertonic saline 