In Arizona, a bus used in commerce generally requires a CDL and passenger endorsement when it is designed to transport:
Correct answer: B – 16 or more people, including the driver
A vehicle designed to transport 16 or more passengers, including the driver, falls within the passenger-carrying commercial motor vehicle threshold. State law also requires a passenger endorsement to operate a bus with that designed capacity. The driver must hold the proper CDL class and complete the required passenger-vehicle testing.
Source: Arizona Commercial Driver License Manual — § 4, “Transporting Passengers Safely”, A.R.S. § 28-3103 — Driver License Endorsements, 49 CFR § 383.5 — Definitions

