(a) A person commits the crime of rape in the first degree if:
(1) He or she engages in sexual intercourse with a member of the opposite sex by forcible compulsion; or
(2) He or she engages in sexual intercourse with a member of the opposite sex who is incapable of consent by reason of being physically helpless or mentally incapacitated; or
(3) He or she, being 16 years or older, engages in sexual intercourse with a member of the opposite sex who is less than 12 years old.
(b) Rape in the first degree is a Class A felony.