You are answering a USMLE-style medical question. Question: A 17-year-old girl comes to the physician because of an 8-month history of severe acne vulgaris over her face, upper back, arms, and buttocks. Treatment with oral antibiotics and topical combination therapy with benzoyl peroxide and retinoid has not completely resolved her symptoms. Examination shows oily skin with numerous comedones, pustules, and scarring over the face and upper back. Long-term therapy is started with combined oral contraceptive pills. This medication decreases the patient's risk developing of which of the following conditions? Options: A) Hypertension B) Ovarian cancer C) Cervical cancer D) Breast cancer Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.