Which of the following is NOT a required item for United flight attendants?

The emergency oxygen mask is not a required item specifically for individual flight attendants to carry. Instead, emergency oxygen masks are part of the aircraft's safety equipment and are installed on board for use by passengers and crew in case of a cabin pressure loss. Flight attendants are trained to ensure that these masks are functional and accessible but do not individually carry them.

In contrast, the United badge, pens, and working flashlight are essential items that flight attendants must personally carry. The badge identifies them as authorized crew members, pens are necessary for completing various documentation and checks, and a working flashlight is critical for safety and operational needs, particularly in low-visibility conditions. Therefore, the emphasis is on the individual responsibility of the flight attendant to have these items, as they relate directly to their duties and safety protocols in providing service and assistance on the flight.