If using information from The National Survey of Sexual Health and Behavior, which statement would best define what is meant by "having sex"?

a. Engaging in vaginal/penile intercourse
b. Engaging in any form of sexual behavior, i.e., anal sex, oral sex, mutual masturbation
c. Engaging in sexual behaviors limited to penetrative sex such as anal and vaginal/penile
d. None of the above as people seem to hold multiple definitions of what "having sex" is

d