Answer:
You must be at least 21 years old to get a class A or B license.
Step-by-step explanation:
In USA class B or C licenses are required for being able to drive buses, tank trucks and carrying hazardous materials. We are also required to apply for the proper endorsements on CDL. Various endorsements include Passenger(P) for carrying passengers, Tank(T) for driving trucks containing liquids, Hazardous(H) for carrying Hazardous materials. Specialized knowledge exam and specialized driving skills test is required for getting an endorsement.
Class A licenses are required for the drivers who want to operate the combination of vehicles with the Gross combination weight rating of 26,001 pounds or more and if the towed vehicle is more than 10,000 pounds. A driver having a class A license can drive Truck-Trailers, Truck and Trailer combinations, Tank Vehicles and flatbeds. It also allows in driving class B and C vehicles. The drivers having a Class B license can operate a single vehicle having a gross combination weight of 26,01 or more pounds, the tow vehicle shouldn't be heavier than 10,000 pounds. With Class B license one can drive Straight trucks, Large passenger buses, Box trucks, Dump Trucks with small trailers.