What is the correct course of action in this situation?

Your answer is correct because when driving on a slippery road, as indicated by the warning sign, it is important to reduce your speed to maintain control. Additionally, avoiding abrupt steering movements helps prevent skidding. Braking hard is not recommended because it can cause the wheels to lock and the vehicle to skid, especially on slippery surfaces. In Germany, the key is to drive smoothly and carefully in such conditions to ensure safety.