<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 65-year-old man comes to the physician because of a 6-month history of muscle weakness. During this period, the patient has had low energy, intermittent nosebleeds, and a 5-kg 11-lb weight loss. He also reports progressive hearing and vision problems. He has a history of pins-and-needles sensation, numbness, and pain in his feet. Vital signs are within normal limits. Physical examination shows a palpable liver tip 23 cm below the right costal margin. There is nontender lympadenopathy in the groins, axillae, and neck. Laboratory studies show:Hemoglobin 8.8 gdLWhite blood cells 6,300mm3Platelet count 98,000mm3Erythrocyte sedimentation rate 70 mmhSerumNa 136 mmolLK 3.6 mmolLCr 1.3 mgdLCa2 8.6 mgdLAspartate aminotransferase 32 ULAlanine aminotransferase 36 ULAlkaline phosphatase 100 ULLactate dehydrogenase 120 ULA serum protein electrophoresis exhibits a sharp, narrow spike of monoclonal IgM immunoglobulin. Which of the following is the most likely diagnosis?? A: Hairy cell leukemia, B: Multiple myeloma, C: Waldenstrom macroglobulinemia, D: Monoclonal gammopathy of undetermined significance, E: Mantle cell lymphoman,  <response>: This is a clinical vignette describing a 65-year-old man with a 6-month history of progressive muscle weakness, fatigue, nosebleeds, weight loss, hearing and vision problems, and numbnesstingling in the feet. Key findings on exam include hepatomegaly, lymphadenopathy, anemia, thrombocytopenia, elevated ESR, monoclonal IgM spike on SPEP, and normal electrolytes, kidney function, and liver enzymes. The progressive symptoms, exam findings of organomegaly and lymphadenopathy, cytopenias, elevated inflammatory markers, and monoclonal protein spike are concerning for a hematologic malignancy. The IgM spike makes plasma cell disorders like multiple myeloma less likely. The leading considerations are Waldenstrom macroglobulinemia, hairy cell leukemia, and mantle cell lymphoma. However, the sharp narrow spike of IgM on SPEP is classic for Waldenstrom macroglobulinemia.C: Waldenstrom macroglobulinemia 