dance programme is scheduled for $10.00$ $a.m$. Some students are participating in the programme and they need to come an hour earlier than the start of the event. These students should be accompanied by a parent. Other students and parents should come in time for the programme. The instruction you think that is appropriate for this is
1. Students should come at $9.00$ $a.m$. and parents should come at $10.00$ $a.m$.
2. Participating students should come at $9.00$ $a.m$. accompanied by a parent, and other parents and students should come by $10.00$ $a.m$.
3. Students who are not participating should come by $10.00$ $a.m$. and they should not bring their parents. Participating students should come at $9.00$ $a.m$.
4. Participating students should come before $9.00$ $a.m$. Parents who accompany them should come at $9.00$ $a.m$. All others should come at $10.00$ $a.m$.