An Adolescent Female Student Who Is Sexually Active Visits the Office

An adolescent female student who is sexually active visits the office of the school nurse.Which of the following statements best reflects the student's understanding of the effective use of contraception devices?

A) "My boyfriend is able to withdraw before ejaculation, and that prevents me from getting pregnant."
B) "I take my temperature every morning, and when it goes down for at least two days, we have unprotected sex."
C) "We use 'foam' before each time we have sex, and I haven't gotten pregnant yet."
D) "We use a condom with a water-based lubricant."