This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Medicine
A patient has Hb 6 gm% ,folic acid 8ng/ml, vitamin B12 60 pg/ml, serum iron 130 microg/dl, and MCV-104. The diagnosis is - 
Select and explain. 
A. Iron deficiency anaemia, B. Vitamin Bl2 deficiency, C. Folic acid deficiency, D. Pyridoxine deficiency
B: Vitamin Bl2 deficiency
Answer: B: Vitamin Bl2 deficiency 
Explanation: <p>Normal range of vit B12 in serum is 280-1000pg/mL.. Values below 100pg/mL indicate clinically deficient stage. </p><p>Normal range of serum folate is 6-18ng/mL. Normal serum iron is 40-140 microgram/dL.In this case it is within normal limit.</p><p>Reference :Harsh mohan textbook of pathology sixth edition pg no 308.</p>