(a) Aggravated rape of a child is the unlawful sexual penetration of a victim by the defendant or the defendant by a victim, if the victim is eight (8) years of age or less.
(b) Aggravated rape of a child is a Class A felony and shall be punished as follows:
(1) If the defendant was a juvenile at the time of the offense, then the sentence must be from within Range III, as set forth in title 40, chapter 35; and
(2) If the defendant was an adult at the time of the offense, then the sentence must be:
(A) Death; or
(B) Imprisonment for life without possibility of parole.