(a) where the defendant stands convicted of such sexual assault against a child and such conviction is for a class A-II or class B felony offense, and the predicate conviction for such sexual assault against a child is for a class A-II, class B or class C felony offense, the court shall impose an indeterminate sentence of imprisonment, the maximum term of which shall be life and the minimum period of which shall be at least fifteen years and no more than twenty-five years;

(b) where the defendant stands convicted of such sexual assault against a child and the conviction is for a class C felony offense, and the predicate conviction for such sexual assault against a child is for a class A-II, class B or class C felony offense, the court shall impose a determinate sentence of imprisonment, the term of which must be at least twelve years and must not exceed thirty years; provided however, that if the court determines that a longer sentence is warranted, the court shall set forth on the record the reasons for such determination and, in lieu of imposing such sentence of imprisonment, may impose an indeterminate sentence of imprisonment, the maximum term of which shall be life and the minimum period of which shall be at least fifteen years and no more than twenty-five years;

(c) where the defendant stands convicted of such sexual assault against a child and the conviction is for a class B felony offense, and the predicate conviction for such sexual assault against a child is for a class D or class E felony offense, the court shall impose a determinate sentence of imprisonment, the term of which must be at least twelve years and must not exceed thirty years;

(d) where the defendant stands convicted of such sexual assault against a child and the conviction is for a class C felony offense, and the predicate conviction for such sexual assault against a child is for a class D or class E felony offense, the court shall impose a determinate sentence of imprisonment, the term of which must be at least ten years and must not exceed twenty-five years;

(e) where the defendant stands convicted of such sexual assault against a child and the conviction is for a class D felony offense, and the predicate conviction for such sexual assault against a child is for a felony offense, the court shall impose a determinate sentence of imprisonment, the term of which must be at least five years and must not exceed fifteen years; and

(f) where the defendant stands convicted of such sexual assault against a child and the conviction is for a class E felony offense, and the predicate conviction for such sexual assault against a child is for a felony offense, the court shall impose a determinate sentence of imprisonment, the term of which must be at least four years and must not exceed twelve years. 5. Notwithstanding subdivision four of this section, where the court has found pursuant to subdivision three of this section that a person: (a) stands convicted of a felony offense defined in article one hundred thirty of this chapter for the commission or attempted commission of a sexual assault against a child; and (b) has been subjected to a predicate felony conviction for sexual assault against a child as defined in subdivision two of this section; and (c) who was under the age of eighteen years at the time of the commission of such predicate felony offense, then the court may, in lieu of the sentence authorized by subdivision four of this section, sentence the defendant to a term of imprisonment in accordance with the sentence authorized for the instant felony offense pursuant to subdivision three of section 70.04 of this article. The court shall set forth on the record the reasons for such determination.