To rest during a trip, it is important to know where you can stop safely and legally. On **motorways and expressways**, it is prohibited to stop or park anywhere other than a **rest or service area**. These areas are specifically designed for drivers to stop safely without interrupting the flow of traffic or endangering road safety.

Rest areas and petrol stations offer an adequate space to stop, allowing drivers to rest, refuel, and use basic services without violating traffic regulations. Stopping in other places, such as on the hard shoulder or on secondary roads of the motorway, is prohibited and can be dangerous, as it could obstruct the passage of other vehicles or create hazardous situations.

Therefore, the correct option is to stop **only at petrol stations or rest areas** to ensure safety and comply with traffic regulations.