Final answer:
In general aviation practice, a green seal on a cart signifies readiness for service, while a red seal indicates non-readiness. It is important for cabin crew to understand this color-coded system. The correct answer is option A.
Step-by-step explanation:
When sealing carts on descent during a flight, different colored seals often have specific meanings. Although practices may vary by airline, a green seal typically signifies that the cart is ready for service and has been restocked or checked for use. In contrast, a red seal generally indicates non-readiness, meaning the cart may need to be replenished or may contain waste or unused items that are not to be served to passengers. It's important for cabin crew to understand the color-coded system to maintain proper in-flight service protocols and safety standards.