Which document must vehicle owners present during their emissions test?

Vehicle owners are required to present the vehicle registration during their emissions test because this document serves as official proof that the vehicle is legally registered for use on public roads. The registration provides necessary information about the vehicle, including its make, model, year, and identification number, which are essential for verifying the specific vehicle being tested.

While other documents like a driver's license may identify the owner, and proof of insurance demonstrates that the vehicle is insured, they do not directly confirm the registration status of the vehicle for testing purposes. A service history report may provide insights into the vehicle's maintenance but is not required for emissions testing. The focus on the vehicle registration ensures that the correct vehicle is being evaluated under emissions regulations.