Why is it important to perform a shoulder check before exiting a vehicle?

Performing a shoulder check before exiting a vehicle is crucial for ensuring both personal safety and the safety of others around you. By checking over your shoulder, you gather essential visual awareness of your surroundings, particularly of any bicycles or vehicles that may be approaching.

In the context of the correct answer, checking for cyclists is vital, especially in urban areas where cyclists might be riding close to parked vehicles. A shoulder check allows you to identify their presence before opening your door, thus preventing accidents that could seriously injure cyclists. Additionally, looking for other vehicles is equally important. This action enables you to see if there are any cars that might be trying to pass closely or could pose a hazard as you exit the vehicle.

Both aspects—checking for cyclists and other vehicles—underscore the importance of being proactive in ensuring a safe exit from the vehicle, making option D the comprehensive and correct choice in this scenario.