(2) not less than five years and up to the natural life of the sex offender for the offense of aggravated criminal sexual penetration, criminal sexual penetration in the first or second degree, criminal sexual contact of a minor in the second or third degree or sexual exploitation of children by prostitution in the first or second degree.
A sex offender's period of supervised parole may be for a period of less than the maximum if, at a review hearing provided for in Subsection C of this section, the state is unable to prove that the sex offender should remain on parole.