<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 72-year-old man presents to the physician with severe lower back pain and fatigue for 3 months. The pain increases with activity. He has no history of a serious illness. He takes ibuprofen for pain relief. He does not smoke. The blood pressure is 10565 mm Hg, the pulse is 86min, the respirations are 16min, and the temperature is 36.7C 98.1F. The conjunctivae are pale. Palpation over the 1st lumbar vertebra shows tenderness. The heart, lung, and abdominal examination shows no abnormalities. No lymphadenopathy is palpated. The results of the laboratory studies show:Laboratory testHemoglobin 9 gdLMean corpuscular volume 90 μm3Leukocyte count 5,500mm3 with a normal differentialPlatelet count 350,000mm3SerumCalcium 11.5 mgdLAlbumin 3.8 gdLUrea nitrogen 54 mgdLCreatinine 2.5 mgdLLumbosacral computed tomography CT scan shows a low-density lesion in the 1st lumbar vertebra and several similar lesions in the pelvic bones. Which of the following is the most likely diagnosis?? A: Metastatic prostatic cancer, B: Multiple myeloma, C: Secondary hyperparathyroidism, D: Small-cell lung carcinoma, E: Waldenstroms macroglobulinemia,  <response>: Based on the information provided in the question stem, this 72-year-old man is presenting with severe lower back pain and fatigue that has been ongoing for 3 months. The pain worsens with activity. Key findings on physical exam include tenderness over the 1st lumbar vertebra and pale conjunctivae. Lab results are significant for anemia with a low hemoglobin, normal MCV, low calcium, decreased albumin, and increased BUN and creatinine. Imaging shows lytic bone lesions in the lumbar spine and pelvis. This presentation is most consistent with multiple myeloma given the patients age, bone pain, anemia, renal dysfunction, hypercalcemia, and lytic bone lesions on imaging. The decreased albumin also supports a plasma cell dyscrasia like multiple myeloma. The other answer choices can be ruled out based on details not fitting with the clinical presentation.B: Multiple myeloma 