Under Article 52 of the Implementation Regulations, when a motor vehicle breaks down on an ORDINARY (non-expressway) road and cannot be moved immediately, at what distance behind the vehicle must the warning triangle sign (警告标志 / 三角牌) be placed?

1. 10 meters to 20 meters behind
2. 50 meters to 100 meters behind (车后50米至100米处)
3. 150 meters to 200 meters behind
4. On top of the vehicle roof