1. A 65-year-old m an was seen at a clinic because of m uscle weakness, em otional instability, burning of the tongue, and alternating constipation and diarrhea. Physical exam ination showed a pale m...

1. A 65-year-old m an was seen at a clinic because of m uscle weakness, em otional instability, burning of the tongue, and alternating constipation and diarrhea. Physical exam ination showed a pale m an w ith red tongue, loss of vibratory sense in the lower extrem ities, and ataxia. Pertinent blood values w ere red blood cell count 3.4 × 106/mm 3 (norm al, m ale 4.3-5.9 × 106/mm3), m ean corpuscular volum e 110 fL (norm al 80-100 fL), vitam in B12 96 pg/m L (norm al > 280 pg/m L), serum ferritin 250 ng/m L (norm al 30-300 ng/m L). Which of the follow ing drugs would be m ost appropriate for this patient? A. Folic acid B. Ferrous sulfate C. Deferoxam ine D. Iron dextran E. Cyanocobalam in