Final answer:
The hazard class that uses transport indexes to determine the amount that can be loaded in a single vehicle is Class 7 - Radioactive Materials.
Step-by-step explanation:
The hazard class that uses transport indexes to determine the amount that can be loaded in a single vehicle is the Class 7 - Radioactive Materials hazard class.
Transport indexes are used to indicate the radiation level emitted by the radioactive material and are used to ensure the safety of transportation.
For example, a transport index of 2 means that a maximum of 2 times the radiation level allowed during transportation can be loaded in a single vehicle.