Sexually Active People Often Underestimate Their Risk of Contracting a Sexually

Sexually active people often underestimate their risk of contracting a sexually transmitted disease

A) because many people who carry STDs remain asymptomatic.
B) because the more common STDs are treatable; and therefore, people easily dismiss their impact on health.
C) because people who are sexually active may have indirect contact with many other people.
D) for all of these reasons.