Suilline

The adjective that's more commonly used to describe a pig is of course 'porcine'. This is derived from porcus, the Latin word for a pig.

Some dictionaries (e.g. The Free Dictionary) define 'suilline' as "of or pertaining to a hog or the Hog family (Suidae)". Collins defines it as "another word for suidian" – 'suidian' being "a pig or related animal, any member of the family Suidae".

According to Wikipedia, the Suidae include pigs, hogs and boars.

Conclusion: while 'porcine' refers specifically to pigs, 'suilline' (or 'suidian') can also refer to hogs or boars. So "hog–like" or "boar–like" should have been allowed as a correct answer.