What must the driver of vehicle 1 observe?

The driver of vehicle 1 must observe the right-of-way of vehicle 3 because understanding right-of-way rules is crucial for safe navigation on the road. Right-of-way principles help determine who has priority in various driving situations, allowing for the smooth flow of traffic and preventing accidents.

In this scenario, vehicle 1 must yield to vehicle 3 based on specific circumstances, such as traffic signals or road conditions, which could dictate that vehicle 3 has the right to proceed. It's important for drivers to be aware of their surroundings and know when they need to yield to other vehicles to maintain safety on the road.

Observing traffic signals is also important, but the question implies a specific situation regarding right-of-way, particularly in relation to other vehicles. Focusing on pedestrians is essential in general driving contexts, but vehicle 1's obligation in this case emphasizes interactions with other vehicles rather than with pedestrians or simply adhering to traffic signals.