Final answer:
A parcel marked with a 'DANGER' label, indicating hazardous material, will be rejected by the crew for transportation on a passenger flight to ensure safety, regardless of its urgency.
Step-by-step explanation:
An item marked with a rectangular, orange DANGER label indicates that the package contains hazardous materials. The urgency of the parcel doesn't outweigh the regulations concerning the transport of such goods. Accordingly, the parcel with a DANGER label will be rejected by the crew for transportation on a passenger flight, according to safety regulations to ensure the safety of everyone on board.