This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'An old man having complaint of anorexia, weakness and paraesthesia. On investigation, his haemoglobin was 5.8g% and peripheral smear showed macrocytes and neutrophils having hypersegmented nuclei. His tendon reflexes were also sluggish. Endoscopy revealed atrophic gastritis. Deficiency of which of the following factor can lead to this situation \nSelect and explain. \nA. Folic acid, B. Riboflavin, C. VitaminB12, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Diagnosis of the patient is pernicious anemia. Factors favouring this diagnosis are:\n\nMegaloblastic anemia.\nDemyelination (decreased tendon reflexes)\nAtrophic gastritis\n\nSo, he would require B12 supplementation.', 'role': 'assistant'}]