Do you have the question number, so we can check if there's something wrong on the site?

Make sure you read the question very carfully, sometimes it reads "who must wear a seatbelt", sometimes it says "wo doesn't have to wear a seatbelt", and then a mistake is easily made.

You don't have to wear a seatbelt when reversing. And a POSTMAN who is delivering packages from door to door doesn't have to wear one either. Other people delivering packages, e.g. a UPS guy, do have to wear their seatbelts.
In a 30km/hr zone you also do have to wear your seatbelt.

Dear all,

When someone must wear a seat belt?

1. when he is reversing
2. when he is delivering packages door to door
3. when he is in a 30 km/hr zone

According to the book, it should be the 3rd as an answer, but at the exercises online and at the test, the answer is 1.

Which one is the correct one?

Thank you in advance.

Panos