(1) Offense Defined.  A male who has sexual intercourse with a female not his wife, or any person who engages in deviate sexual intercourse or causes another to engage in deviate sexual intercourse, is guilty of an offense if:

  (a) the other person is less than [16] years old and the actor is at least [4] years older than the other person;  or

  (b) the other person is less than 21 years old and the actor is his guardian or otherwise responsible for general supervision of his welfare;  or

  (c) the other person is in custody of law or detained in a hospital or other institution and the actor has supervisory or disciplinary authority over him; or

  (d) the other person is a female who is induced to participate by a promise of marriage which the actor does not mean to perform.

 (2) Grading.  An offense under paragraph (a) of Subsection (1) is a felony of the third degree.  Otherwise an offense under this section is a misdemeanor.