<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 71-year-old man comes to the physician for a health maintenance examination. Aside from occasional lower back pain in the last couple of years, he feels well. He had a right-sided myocardial infarction 4 years ago. Currently, he has no shortness of breath and has no anginal symptoms. He has a 30 pack-year history of smoking but stopped smoking 10 years ago and does not drink alcohol. His pulse is 59min, and his blood pressure is 13575 mm Hg. Physical examination reveals 1 lower extremity edema. Cardiac and pulmonary auscultation show no abnormalities. There is no lymphadenopathy. His laboratory studies show a hemoglobin of 13.2 gdL and serum protein of 10.1 gdL. ECG shows known Q wave abnormalities unchanged since the last ECG one year ago. A serum protein electrophoresis with immunofixation is shown. Which of the following is the most appropriate next step to establish the diagnosis?? A: Bone densitometry, B: Rectal biopsy, C: Echocardiography, D: Whole-body CT scan, E: Urine dipstickn,  <response>: This is a clinical vignette describing a 71-year-old man with a history of myocardial infarction 4 years ago who is asymptomatic and presenting for a routine health maintenance exam. Key findings on history and physical exam include occasional lower back pain, prior MI, 30 pack-year smoking history quit 10 years ago, no anginal symptoms, pulse 59min, BP 13575 mm Hg, 1 lower extremity edema, and unremarkable cardiac and pulmonary exam. Lab studies show normal hemoglobin and serum protein. ECG shows unchanged Q wave abnormalities compared to 1 year ago. Serum protein electrophoresis with immunofixation was performed and showed abnormal results. Based on the information provided, the most likely diagnosis is a plasma cell disorder such as multiple myeloma. The serum protein electrophoresis and immunofixation indicate the presence of an abnormal monoclonal protein. The next step would be to establish the diagnosis and determine the extent of disease. Of the answer choices provided, a whole body CT scan would be the most appropriate next step to evaluate for lytic bone lesions and other evidence of multiple myeloma. An echocardiogram and bone densitometry would not help establish this diagnosis. A rectal biopsy would be useful if amyloidosis was suspected based on clinical features, but this patient does not have symptoms suggestive of amyloidosis. A urine dipstick would not be helpful in establishing the diagnosis.D: Whole-body CT scan 