What is the right course of action now?

Your chosen answers are correct because when you encounter an obstacle such as an accident or stationary vehicles blocking your lane, German traffic rules require you to slow down to a safe speed to assess and react appropriately. Reducing your speed helps prevent accidents and gives you better control under potentially hazardous conditions.

At the same time, you must move as far to the left as possible to safely bypass the obstacle, even if that means temporarily driving in the oncoming lane—provided it is safe and the lane is clear. This movement should always be done with appropriate signaling to inform other drivers of your intentions.

Continuing to drive just as before without slowing down or steering away from the obstacle would be unsafe and against traffic regulations. Thus, the combination of reducing speed and shifting left is the correct and responsible action to take when faced with a blocked lane ahead.