Regarding Studies of Sexually Active Teenagers, Which of the Following

Regarding studies of sexually active teenagers, which of the following statements is/are TRUE?

A) Nearly 90 percent of the teenage girls in one study thought that they had no chance of getting an STD, but one in four got chlamydia or gonorrhea within the next 18 months.
B) A recent study of sexual relationships at a high school in a Midwestern city found long chains of sexual contact between students.
C) A student in the Midwestern high school study who had sex with only one person was shown to have indirect contact with dozens of other students.
D) All of these were findings in the two studies on sexually active teenagers.