What inhibits the operation of a three-point seatbelt?

The selected combination correctly identifies three factors that can inhibit the effectiveness of a three-point seatbelt. In German traffic regulations, it's crucial that seatbelts are worn properly to ensure maximum safety during a vehicle operation.

Wearing a thick winter coat can create extra space between the body and the seatbelt, reducing its restraining effectiveness in the event of a collision. Passing the seatbelt under both arms instead of over the shoulder compromises its ability to securely hold the occupant, as it may not distribute forces evenly during an accident. Lastly, if the belt is not fully locked into the harness buckle, it may not function at all, increasing the risk of injury.

In summary, all three factors are important to consider for proper seatbelt use, as each directly affects the safety of the occupant according to German traffic safety laws. Always ensure that the seatbelt is used correctly and is properly fastened to ensure optimal protection.