(a) Except as provided by this chapter, a person commits an offense if the person knowingly manufactures, delivers, or possesses with intent to deliver a controlled substance listed in Penalty Group 1-A.
(b) An offense under this section is:
(1) a state jail felony if the number of abuse units of the controlled substance is fewer than 20;
(2) a felony of the second degree if the number of abuse units of the controlled substance is 20 or more but fewer than 80;
(3) a felony of the first degree if the number of abuse units of the controlled substance is 80 or more but fewer than 4,000; and
(4) a felony of the first degree punishable by imprisonment in the Texas Department of Criminal Justice for life or for a term of not more than 99 years or less than 15 years and a fine not to exceed $250,000, if the number of abuse units of the controlled substance is 4,000 or more.