A 15-year-old girl is brought to the physician's office by her mother because she thinks that her daughter is having abnormal bleeding. The patient had her first menses 18 months before the office visit. Which of the following characterize bleeding in young women of this age?

• A. Regular cycles with heavy menses
• B. Midcycle spotting
• C. Anovulatory bleeding
• D. Progesterone withdrawal bleeding