When Peter Bearman and His Colleagues Analyzed the Sexual Habits

When Peter Bearman and his colleagues analyzed the sexual habits of teenagers,they found that a person does not date the ex of the person's ex's boyfriend or girlfriend.This "no cycles of four" rule seems to operate:

A) in middle school but not in high school.
B) without anyone being consciously aware of it.
C) as a result of sex education in public schools.
D) only within certain ethnicities.