While Educating a Patient with Diabetes About the HbA1c Test

While educating a patient with diabetes about the HbA1c test, a nurse teaches that the HbA1c gives a better overall picture of glycemic control by measuring the amount of glucose present over a period of

A) 1 to 2 months.
B) 4 to 5 months.
C) 2 to 3 months.
D) 3 to 4 months.