Why do you have to switch to the right-hand lane?

In this scenario, the question asks why you have to switch to the right-hand lane. The correct answer is the red car (answer 1).

According to German traffic rules, when a lane splits off or a new right-hand lane is available, you must use the right lane whenever possible, especially outside built-up areas ("Rechtsfahrgebot" – keep right rule). Staying in the left lane is only allowed for overtaking or when traffic conditions require it, such as preparing for a left turn or if signs direct you otherwise.

In this case, there is no reason to stay in the left lane: the right lane is available and safe, so you are required to move right. This rule ensures smooth flow of traffic and safety for all road users.

Remember: On multi-lane roads outside of cities in Germany, always use the rightmost lane that is free. Only remain left for overtaking or if indicated by traffic signs. This will help you answer similar questions correctly in the future.