Which of the following is not a valid requirement for operation of a Class A MDC?

The operation of a Class A Motor Driven Cycle (MDC) does not require the rider to wear a seatbelt because MDCs, which often include motorcycles and scooters, are designed without seatbelts. Unlike passenger vehicles where seatbelts are a standard safety feature, motor-driven cycles rely on the rider's ability to maintain stability and control without the need for seatbelts.

Other options serve as necessary requirements for operating a Class A MDC. For instance, having a registered Class A license ensures the operator has met the state requirements for motorcycle operation, while carrying no more than one passenger aligns with safety regulations that dictate passenger limits to maintain balance and control on the vehicle. Additionally, a motorcycle endorsement is crucial as it signifies that the operator has undergone the necessary training and testing specific to motorcycles, which have different handling and operational characteristics than standard vehicles.

In summary, while seatbelts are critical for safety in many types of vehicles, they are not applicable or required for the operation of Class A MDCs, making that choice the correct answer.