The document certifying that a motorbike has been approved for use is:

The question is about the document that approves a motorcycle for road use. It is the vehicle registration certificate - the answer is A.

The Road Traffic Act states that the document confirming that a motor vehicle - and therefore also a motorcycle - is approved for road use is the vehicle registration certificate or a temporary permit, issued by the starost (head of the district authority) together with validated number plates. A driving licence (answer B) confirms the driver's entitlement, not the approval of the vehicle; an identity card (answer C) only confirms identity. The vehicle registration certificate contains the data of the vehicle and its owner and the date of the next technical inspection - only a valid inspection and valid third-party liability insurance (OC) make it legal to ride the motorcycle. Since 2018 you do not have to carry the vehicle registration certificate with you, because the police officer checks it in the Central Register of Vehicles, but the document exists, and if the vehicle has a defect it can be "retained" electronically - then you must not ride the vehicle until the defect has been repaired and it has passed a technical inspection, apart from any permission entered in the receipt (for a maximum of 7 days).

Legal basis: Art. 71 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym); Art. 38 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)