What must be ensured regarding the refuse cart during preflight checks?

Ensuring that the refuse cart is lined and functioning correctly is crucial during preflight checks because it directly impacts the cleanliness and hygiene of the aircraft. A lined cart contains any waste securely, preventing spills and odors from leaking into the cabin, which can lead to unpleasant conditions for both passengers and crew. Additionally, confirming that the cart is functioning correctly means the mechanisms used for opening, closing, and securing the cart are operational, ensuring safety and efficiency during waste management throughout the flight. Proper management of refuse is essential for maintaining an appealing environment onboard, aligning with industry health standards and customer expectations.