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
Pernicious anaemia is associated with the deficiency of: 
Select and explain. 
A. Folic acid, B. Vitamin B1, C. Vitamin B6, D. Vitamin B12
D: Vitamin B12
Answer: D: Vitamin B12 
Explanation: None