A 65-Year-Old Woman Was Admitted to the Hospital in Mild

A 65-year-old woman was admitted to the hospital in mild congestive heart failure.She complained of a burning sensation in her calves and feet and of weight loss.Upon admission she appeared confused,depressed,and pale.She had some edema around her ankles.Her lab results were as follows: low hemoglobin and hematocrit,increased RBC size,decreased RBC and WBC count,and hypersegmented neutrophils.All basic chemistry values were normal.Which vitamin should be tested for deficiency?

A) Vitamin A
B) Vitamin B₁₂
C) Vitamin C
D) Vitamin D