请根据下面短文回答下列题：
Safety Rules for Bike-Riding.
1. Never ride out into a street without stopping first.
2. Watch for stop signs.
3. Look behind before turning or changing lanes (车道) .
4. Always ride on the right.
5. Never follow another rider without applying the rules.
Remember, your bicycle is a small compared with cars and trucks. It is not easily seen on crowded streets and will seldom attract attention on its own. At all times, do everything you can to make sure you are noticed.
What should a bike-rider do when he / she rides after another rider
[A] Watches for stop signs.
[B] Changes lanes.
[C] Applies the safety rules.