"adult person" means a person who is of or above the age of 18 years.
"child" means a person who is under the age of 16 years.
"unlawful sexual activity" means an act that constitutes an offence under this
Division or Division 10A, 15 or 15A (or, in the case of an act occurring
outside this State, that would constitute such an offence if it occurred in
this State).