A45-year-old female with a past medical history of rheumatoid arthritis presents to the emergency department with right calf pain and swelling of sudden onset. she denies fever, chills, dyspnea, chest pain, or history of trauma to the leg. she has smoked a half pack of cigarettes daily for 20 years. her only medicine is methotrexate for her rheumatoid arthritis. on physical examination, her temperatureis 37.0°c (98.6.f), pulse is 70/min, blood pressure is 140/80 mmhg, and respirations are 14/min. her bmi is 30 kg/m2. examination of the right calf reveals mild redness, warmth and tenderness. whichof the following is the most appropriate next step in the management of this patient? a. initiate warfarin therapyb. initiate heparin therapyc. perform compression ultrasonographyd. perform contrast venographye. obtain blood cultures and start antibiotics