17.—(1) A person aged 18 or over (A) commits an offence if—
(a)he intentionally causes or incites another person (B) to engage in an activity,
(b)the activity is sexual, and
(c)either—
(i)B is under 16 and A does not reasonably believe that B is 16 or over, or
(ii)B is under 13.
(2) A person guilty of an offence under this Article, if the activity caused or incited involved—
(a)penetration of B's anus or vagina,
(b)penetration of B's mouth with a person's penis,
(c)penetration of a person's anus or vagina with a part of B's body or by B with anything else, or
(d)penetration of a person's mouth with B's penis,
is liable, on conviction on indictment, to imprisonment for a term not exceeding 14 years.
(3) Unless paragraph (2) applies, a person guilty of an offence under this Article is liable—
(a)on summary conviction, to imprisonment for a term not exceeding 6 months or a fine not exceeding the statutory maximum or both;
(b)on conviction on indictment, to imprisonment for a term not exceeding 14 years.