3. Данное предложение говорит о запрете, правиле, поэтому используем оборот are not allowed to или mustn't.
Kids under sixteen are not allowed to go out after 10 p.m. due to the curfew.
ИЛИ
Kids under sixteen mustn't go out after 10 p.m. due to the curfew.
Ответ: Kids under sixteen are not allowed to go out after 10 p.m. due to the curfew. ИЛИ Kids under sixteen mustn't go out after 10 p.m. due to the curfew.