Which Explanation of a Marginal Placenta Previa Would the Nurse

Which explanation of a marginal placenta previa would the nurse provide to her client?

A) The placenta is in the lower uterus, completely covering the internal cervical os.
B) The placenta is in the lower uterus, more than 3 cm from the internal cervical os.
C) The placenta is in the lower uterus, less than 3 cm from the internal cervical os.
D) The placenta is in the lower uterus, at the edge and partially covering the cervical os.