Final answer:
To determine which car is not using the roundabout correctly, observe whether it yields to other vehicles and merges correctly. A car that fails to yield or merges in an incorrect manner is not using the roundabout correctly.
Step-by-step explanation:
To determine which car is not using the roundabout correctly, we need to understand the correct way to use a roundabout. When entering a roundabout, drivers should yield to vehicles already in the roundabout, and then merge into the flow of traffic, moving in a counterclockwise direction. The car that fails to follow these rules and fails to yield to other vehicles or merges in an incorrect manner is the car that is not using the roundabout correctly.
For example, if there is a car that enters the roundabout without yielding to cars already in the roundabout, it is not using the roundabout correctly. Or if there is a car that abruptly changes lanes or exits the roundabout from the wrong lane, it is not using the roundabout correctly.
It is important for drivers to understand and follow the correct rules and procedures when using a roundabout to ensure the safety and efficiency of traffic flow.