What is a key difference between how lifejacket rules apply to children aged under 12 compared to adults on a small powerboat?

1. Children under 12 never need to wear a lifejacket
2. Special trigger rules exist for when children under 12 are aboard, such as counting as being 'alone' with the skipper for enclosed-water lifejacket requirements
3. Only adults are required to wear lifejackets
4. Children under 12 are exempt from all boating safety rules