<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 60-year-old man presents to the emergency department for fatigue and feeling off for the past week. He has not had any sick contacts and states that he cant think of any potential preceding symptoms or occurrence to explain his presentation. The patient has a past medical history of diabetes, hypertension, and congestive heart failure with preserved ejection fraction. His temperature is 98F 36.7C, blood pressure is 12565 mmHg, pulse is 90min, respirations are 14min, and oxygen saturation is 100 on room air. Laboratory values are obtained and shown below.Hemoglobin: 12 gdLHematocrit: 36Leukocyte count: 6,500mm3 with normal differentialPlatelet count: 197,000mm3Serum:Na: 147 mEqLCl-: 105 mEqLK: 4.1 mEqLHCO3-: 26 mEqLBUN: 21 mgdLGlucose: 100 mgdLCreatinine: 1.1 mgdLCa2: 10.1 mgdLAST: 12 ULALT: 10 ULUrine:Appearance: clearSpecific gravity: 1.003The patient is admitted to the floor, a water deprivation test is performed, and his urine studies are repeated yet unchanged. Which of the following is the best next step in management?? A: Administer demeclocycline, B: Administer desmopressin, C: Administer hypotonic fluids, D: Obtain a serum renin:aldosterone ratio, E: Perform a head CT,  <response>: This is a clinical case scenario about a 60-year-old man presenting with fatigue and malaise. The key findings are:- Normal vital signs except tachycardia- Past medical history of diabetes, hypertension, congestive heart failure- Normal CBC and basic metabolic panel except low urine specific gravity- Water deprivation test did not concentrate urineThis presentation is most consistent with diabetes insipidus given the polyuria suggested by low urine specific gravity that does not improve after water deprivation. The answer choices provide different options for management. Choice A and B are medications to treat diabetes insipidus - demeclocycline reduces urine output while desmopressin replaces ADH. Choice C of hypotonic fluids would be incorrect in DI. Choice D may help distinguish nephrogenic vs central DI but is not the best next step. Choice E of head CT would not be indicated at this point.B: Administer desmopressin 