A nurse in the emergency department is caring for a client who is concerned about an unplanned pregnancy after having unprotected intercourse with a casual acquaintance last evening. Which of the following statements by the nurse regarding emergency contraception is correct?

Rationale: A. Emergency contraception does not protect against sexually transmitted infections (STIs). B. Emergency contraception is not 100% effective; effectiveness varies depending on timing and method used. C. Emergency contraception is most effective when taken as soon as possible, generally within 120 hours (5 days) after unprotected intercourse, making the client a candidate. D. Emergency contraception prevents pregnancy by delaying ovulation and does not terminate an existing pregnancy.