<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 61-year-old man presents to the emergency room with a painful, swollen left leg. He states that his symptoms began that morning after a long flight from Australia. He denies shortness of breath, chest pain, or cough. On review of systems, he notes that he has been constipated recently and had several episodes of bright red blood per rectum. He has not noticed any weight loss, fevers, or night sweats. He has a past medical history of a deep vein thrombosis 4 years ago during a hospitalization for community acquired pneumonia and was treated with warfarin for 3 months afterward. He also has chronic hepatitis C from previous intravenous drug use. The patient has a 30 pack-year smoking history and has never had a colonoscopy. His father is 84-years-old and has chronic kidney disease from diabetes, and his mother passed away from a massive pulmonary embolus when pregnant with his younger sister. In the emergency room, his temperature is 98.7F 37.1C, blood pressure is 14285 mmHg, pulse is 79min, and respirations are 14min. On exam, he is in no acute distress. His left calf is larger in caliber than the right calf which is red and tender to palpation. Dorsiflexion of the foot worsens the pain. His abdomen is soft, nontender, and nondistended without hepatomegaly. The remainder of the physical exam is unremarkable. Labs are shown below:Hemoglobin: 13.0 gdLLeukocyte count: 6,000mm3Platelets: 160,000mm3Aspartate aminotransferase: 15 ULAlanine aminotransferase: 19 ULAlkaline phosphatase: 81 IULHepatitis C antibody: reactiveHepatitis C titer: 0 copiesmLWhich of the following is the most likely cause of this patients condition?? A: Protein C deficiency, B: Increased estrogen levels, C: Loss of antithrombin III in urine, D: Resistance of factor V to inactivation by protein C, E: Malignancy,  <response>: This is a clinical vignette describing a 61-year-old man presenting with left leg pain and swelling. Key findings include:- Painful, swollen left leg that started after a long flight - History of DVT 4 years ago- Recent constipation and bright red blood per rectum- Family history of DVTPE in mother- Unremarkable vital signs and physical exam except for left calf swelling and tenderness- Normal labs except reactive hepatitis C antibody and 0 viral copiesThe stem asks for the most likely cause of his condition. Based on the history of prior DVT, family history of clots, recent long flight, and unilateral leg swelling, this is most consistent with acute DVT. The choices describe different inherited and acquired thrombophilias. Choice D, resistance of factor V to inactivation by protein C, is consistent with factor V Leiden mutation, which is a common inherited thrombophilia. This is the most likely diagnosis in a patient with recurrent idiopathic DVTs and a family history of clots.D: Resistance of factor V to inactivation by protein C 