What situation applies according to this traffic sign?

You selected the correct answer because this traffic sign indicates a speed limit of 30 km/h that applies specifically for noise protection ("Lärmschutz") between 22:00 (10 pm) and 6:00 (6 am). This means that the reduced speed is enforced only during nighttime hours to minimize noise disturbance. Outside these hours, the speed limit does not apply.

In German traffic rules, such supplementary signs with time intervals specify when the main restriction is active. This helps drivers know exactly when to slow down, improving safety and reducing noise in residential or sensitive areas during night hours.