The authority to downgrade a charge is with the prosecutor. Your few facts do not indicate whether this downgrade was offered through your attorney, or whether you are representing yourself. If you are not represented, I urge you to consult with an experienced criminal defense lawyer before you make any decisions on how to resolve the case, as the lawyer can advise you, among other things, on whether this plea offer is the typical downgrade for the charge, or whether there are any other alternatives based upon a complete understanding of the facts of the case. Good luck.
This response does not constitute legal advice. Given the nature of this website, it does not create an attorney-client relationship. This answer is provided solely for informational purposes, for you to use as a starting point when speaking directly with a lawyer in your State. I urge you to immediately contact an experienced criminal defense lawyer admitted to practice law in your State before you make any decisions about this case.