Which allowed hazardous-material limit is correct for passenger buses under the Maryland CDL manual?

1. No more than 500 pounds total of allowed hazardous materials, and no more than 100 pounds of any one class
2. No more than 1,000 pounds total, with no class limit
3. No more than 500 pounds of any one class, with no total limit
4. Any amount if the driver has a Passenger endorsement