<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 54-year-old man comes to the physician because of generalized fatigue and numbness of his legs and toes for 5 months. He has hypertension and hypercholesterolemia. He underwent a partial gastrectomy for peptic ulcer disease 15 years ago. Current medications include amlodipine and atorvastatin. He is a painter. His temperature is 37C 98.6F, pulse is 101min, respirations are 17min, and blood pressure is 12282 mm Hg. Examination shows conjunctival pallor and glossitis. Sensation to vibration and position is absent over the lower extremities. He has a broad-based gait. The patient sways when he stands with his feet together and closes his eyes. His hemoglobin concentration is 10.1 gdL, leukocyte count is 4300mm3, and platelet count is 110,000mm3. Which of the following laboratory findings is most likely to be seen in this patient?? A: Decreased serum iron levels, B: Oligoclonal bands in cerebrospinal fluid, C: Elevated methylmalonic acid levels, D: Basophilic stippling on peripheral smear, E: Positive rapid plasma reagin test,  <response>: This is a clinical vignette describing a 54-year-old man with fatigue, numbness in his legs and toes, and findings on exam such as pallor, glossitis, decreased vibration and position sense in his lower extremities, and a broad-based gait. His history is notable for hypertension, hypercholesterolemia, and partial gastrectomy for peptic ulcer disease. The key findings pointing to the diagnosis are:- Conjunctival pallor and glossitis suggest anemia- Decreased vibration and position sense in lower extremities suggest peripheral neuropathy- Broad-based gait and swaying with eyes closed suggest sensory ataxiaHis anemia along with peripheral neuropathy and sensory ataxia are consistent with vitamin B12 deficiency, which can occur after gastrectomy due to decreased intrinsic factor production needed for B12 absorption. The lab finding most likely to confirm vitamin B12 deficiency is elevated methylmalonic acid levels, which is a sensitive marker of functional B12 deficiency. The other answer choices would not be expected based on the clinical scenario.C: Elevated methylmalonic acid levels 