You Look Over the Laboratory Reports of 500 Medical Students

You look over the laboratory reports of 500 medical students to determine the frequency of iron deficiency in this population.The best way to identify iron deficiency from laboratory reports would be to define as iron-deficient all those with:

A) A hematocrit below 50%.
B) A reduced level of serum transferrin.
C) An elevated level of serum ferritin.
D) A transferrin saturation of less than 15%.
E) An iron concentration of less than 5 mg/liter in the urine.