Patient 67 years old with involuntary tingling of hands and feet and macrocytic anemia dx?

Patient 67 years old with involuntary tingling of hands and feet and macrocytic anemia dx?

A) Potasium deficiency
B ) Niacin deficiency
C) Cyanocobalamin deficiency
D) Folic acid
E) Calcium deficiency

ans: Cyanocobalamin deficiency