What do you need to consider in this situation?

Your answer is fully correct. According to German traffic rules, when you approach a stationary bus, you must be prepared for people to cross the road unexpectedly. Passengers might get off the bus and walk directly into traffic, so you must be very cautious. To ensure safety, the law (§ 20 StVO) requires you to pass the stationary bus only at walking speed. This slow speed gives you enough time to react to pedestrians and avoid accidents. You are allowed to pass the bus, but only with this extreme care and low speed. The option stating you must not pass a stationary bus is incorrect because passing is allowed, but under strict conditions. Understanding this rule keeps both pedestrians and drivers safe in such traffic situations.