Emily Can Use Her Method of Birth Control "Perfectly" but Still

Emily can use her method of birth control "perfectly" but still has a 26 per cent chance of becoming pregnant. Which of the following is likely true of Emily?

A) She is nulliparous and using condoms alone.
B) She is parous and using a diaphragm.
C) She is nulliparous and using the sponge.
D) She is parous and using the cervical cap.