What is the right course of action?

Your answer is fully correct. According to German traffic rules, the sign shown indicates a priority junction where the main road is running straight, and side roads have to yield.

1. You must allow the motorcycle to go first because it is coming from the main road on your left, and motorcycles have priority here.

2. You take priority before the bus because the bus is entering from a side road and must yield to traffic on the main road.

This means you must first let the motorcycle pass, then you proceed before the bus. Understanding priority signs and right-of-way rules at junctions helps ensure smooth and safe traffic flow.