When are you not allowed to drive a motorized bicycle on public roads?

Your answer is correct because German traffic laws require motorized bicycles to meet specific conditions to be allowed on public roads. Firstly, having valid motor vehicle liability insurance is mandatory; without it, you cannot legally operate the vehicle. Secondly, the motorized bicycle must be roadworthy, meaning it must comply with safety standards and be in proper working condition. Without these requirements, driving on public roads is prohibited to ensure safety for all road users. The payment of motor vehicle tax is not a condition for motorized bicycles, which is why option 3 is not included in the correct answer. Remembering these key points will help you identify when motorized bicycles are legally permitted on the road.