You do not have a Hazardous Materials Endorsement on your commercial driver's license. You can drive a vehicle hauling hazardous materials when?

The correct answer is based on the regulations governing the transportation of hazardous materials. A commercial driver can operate a vehicle that is hauling hazardous materials as long as the vehicle is not required to display placards. Placards are necessary for vehicles carrying certain quantities or types of hazardous materials, as they inform others on the road about the potential dangers. Therefore, if the materials being transported do not meet the criteria for placarding, a driver does not need a Hazardous Materials Endorsement to operate that vehicle.

This option reflects the legal framework that allows for some exemptions when the risk of transporting hazardous materials is deemed low enough not to warrant additional regulatory requirements, such as placarding. The other options do not accurately capture the conditions under which a driver can operate a vehicle carrying hazardous materials without the appropriate endorsement.