What is true about using the hard shoulder in this situation?

Your answer that the hard shoulder must be used like a right-hand lane is correct in this situation.

In Germany, under certain conditions indicated by traffic signs or signals, the hard shoulder can be opened for regular traffic to ease congestion, effectively acting as an additional lane on the right. This is often used during traffic jams or roadworks. Here, the signs and lane markings show that the hard shoulder is legally used as a driving lane, so vehicles can drive there like in a normal lane.

Normally, the hard shoulder is reserved for emergencies, breakdowns, or emergency vehicles. Options stating it can only be used for breakdowns or only by trucks do not apply here, because the signs indicate a temporary change in traffic rules allowing all vehicles to use it as a right lane.

Understanding this helps you recognize when the hard shoulder is legally part of the road for driving and when it is not, which is crucial for safe and lawful driving in Germany.