Flexo Trucking Company transports hazardous waste. Garn is a Flexo driver, whom the company knows drives longer hours than federal regulations permit. One night, Garn exceeds the limit and has an accident. Spilled chemicals contaminate Hill City's water source, forcing the residents to move away. Flexo acted unethically because

Fleet showed reckless disregard for Hill City's residents and others.

Explanation:

Fleet acted unethically because they only cared about their own benefit and didn't care anything about the welfare of the community (not only Hill City but all the other towns and cities) or the well being of their drivers.

The fact that Garn drived longer hours than the federal regulations limit is not unethical, it's a crime.

This accident was the direct result of a negligent act, not an unfortunate accident.

Hill City is not responsible for the illegal acts truck drivers (or any driver at all) may or may not perform.