(a) If any person shall willfully and unlawfully resist, delay or obstruct a public officer in discharging or attempting to discharge an official duty, the person is guilty of a Class 2 misdemeanor.
(b) If any person shall willfully and unlawfully resist, delay, or obstruct a public officer in discharging or attempting to discharge an official duty, and the resistance, delay, or obstruction is the proximate cause of a public officer's serious injury, the person is guilty of a Class I felony.
(c) If any person shall willfully and unlawfully resist, delay, or obstruct a public officer in discharging or attempting to discharge an official duty, and the resistance, delay, or obstruction is the proximate cause of a public officer's serious bodily injury, the person is guilty of a Class F felony.
(d) "Serious bodily injury" is defined as bodily injury that creates a substantial risk of death, or that causes serious permanent disfigurement, coma, a permanent or protracted condition that causes extreme pain, or permanent or protracted loss or impairment of the function of any bodily member or organ, or that results in prolonged hospitalization.