Upon an indictment for incest the accused person may be convicted of –

(a) penetrative sexual abuse of a child [ or young person];

(ab) penetrative sexual abuse of a child [ or young person] by a person in a position of authority;

(b) penetrative sexual abuse of a person with a mental impairment;

(c) indecent act with or directed at a child [ or young person] by a person in a position of authority;

(ca) indecent assault of child [ or young person] by a person in a position of authority;

(d) indecent assault.

(e) .  .  .  .  .  .  .  .