(a) A person commits rape if he engages in sexual intercourse or deviate sexual activity with another person:

(1) By forcible compulsion; or

(2) Not his spouse, who is a patient or resident of a hospital, nursing home, human development center, or other similar facility, and who is incapable of consent because he is mentally defective or mentally incapacitated; or

(3) Who is incapable of consent because he is physically helpless; or

(4) Who is less than fourteen (14) years of age. It is an affirmative defense to prosecution under this subdivision (a)(4) that the actor was not more than two (2) years older than the victim; or

(5) Not his spouse who is less than sixteen (16) years of age and who is incapable of consent because he is mentally defective or mentally incapacitated.

(b) Rape is a Class Y felony.