Which items are prohibited on United Airlines flights?

The correct answer highlights the items that pose a serious risk to passenger safety and security during flights. Weapons, illegal drugs, and hazardous materials are strictly prohibited on all airlines, including United Airlines, due to regulations enforced by aviation authorities.

Weapons can pose a significant danger to passengers and crew, while illegal drugs can have legal consequences and impact the safety of the flight environment. Hazardous materials, such as flammable substances or toxic chemicals, can endanger not only the aircraft but also the lives of everyone on board.

This understanding of regulatory compliance is essential for flight safety and ensures a secure travel experience for all passengers. The nature of items in the other choices does not carry the same level of risk and, in many cases, may even be allowed under certain conditions, which is why they do not represent prohibited items in the same critical manner as those listed in the correct answer.