A slow-moving vehicle emblem may not be displayed on which of the following?

The correct answer is that a slow-moving vehicle emblem may not be displayed on a driveway entrance because this location does not qualify as a part of the vehicle itself and could mislead drivers about the vehicle's status. The purpose of the emblem is to alert other road users that the vehicle is moving slowly, which is essential on public roads.

Displaying it on the rear window, passenger door, or bumper contributes to visibility and safety by clearly indicating the vehicle's slow speed to other drivers. However, placing the emblem at a driveway entrance offers no benefit to oncoming traffic and may create confusion regarding which vehicle is associated with the slow-moving status. Thus, the driveway entrance is not an appropriate location for the emblem to be recognized as an effective warning.