The exhaust noise has suddenly become unusually loud. What is the right thing to do?

Your answer is correct because the sudden increase in exhaust noise usually indicates a problem with the exhaust system, such as a loose or damaged mounting. According to German traffic rules, you must immediately check the exhaust system to identify any faults. If damage is found, it must be repaired promptly to prevent further issues and to comply with noise limits. It is not permitted to exceed exhaust noise limits at any time, even temporarily, to avoid safety hazards and legal consequences. Therefore, options 1 and 2 are the proper actions to take.