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: Pathology
Megaloblastic anaemia occurs due to deficiency of 
Select and explain. 
A. Niacin, B. Vitamin C, C. Vitamin B1, D. Vitamin B12
D: Vitamin B12
Answer: D: Vitamin B12 
Explanation: None