This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET Jan 2020, Subject name: Physiology
A 50 year old man presents with paresthesia. Hb = 6.8 gms/dl. Peripheral smear shows macrocytes and neutrophis with hypersegmented nuclei. Endoscopy reveals atroghic gastritis. Which of the following deficiency is more likely? 
Select and explain. 
A. Fotate deficiency, B. Vitamin B12 deficiency, C. Riboliavan deficiency, D. Fotate deficiency
B: Vitamin B12 deficiency
Answer: B: Vitamin B12 deficiency 
Explanation: above clinical features point towards Vit B12 deficiency due to Pernicious anemia. Pernicious anemia -Type II Hypersensitivityin which ABs are formedagainst intrinsic factorthus inhibits the binding of IF+B12. Intrinsic factor deficiency-Malabsorption of vitamin B12 - Megaloblastic anemia /Pernicious anemia