Under federal regulation, what may a vehicle carrying passengers for hire transport in the way of hazardous materials?

Explanation

Small-arms ammunition and emergency shipments of drugs, chemicals, and hospital supplies are allowed, anything else hazardous is barred where other practicable means of transportation is available, and Class 1 explosive material other than small-arms ammunition may never travel in the passenger-carrying space. 49 CFR 177.870(b) sets the general prohibition together with those narrow exceptions, and 49 CFR 177.870(c) adds the separate rule for the passenger-carrying space of a motor vehicle transporting passengers for hire, so the two work as a general restriction plus a hard floor. The structure matters because the first test a driver applies is whether the shipment could reasonably travel another way, not whether it happens to be properly labeled. The wrong options each collapse one of those rules: labeling and shipping papers do not open a bus to general hazmat, the prohibition is not absolute across all materials, and separating the load from the passengers neither removes the other-practicable-means condition nor makes an unlimited quantity acceptable.

Source: 49 CFR 177.870(b) and (c)