Problem: A patient is taking a combined hormonal oral contraceptive to prevent pregnancy. The patient should be instructed that a backup method of contraception should be used: Need Assignment Help? • A - if they experience symptoms of pelvic inflammatory disease. • B - if irregular menses occurs. • C - if amoxicillin-clavulanate (Augmentin) is prescribed for a sinus infection. • D - if two consecutive doses of the oral contraceptive are missed.