Where are stickers and signs allowed on a vehicle's windshield?

Stickers and signs are allowed on a vehicle's windshield specifically in a limited area to ensure that the driver's visibility is not obstructed. The regulation permits placement within a seven-inch square in the lower corner of the windshield. This restriction is crucial for maintaining a clear line of sight while driving, which enhances safety for both the driver and other road users. Proper placement in this designated area also helps law enforcement recognize and verify the legality of the stickers or signs, such as registration or inspection decals, without interfering with the driver's ability to see the road, vehicles, and pedestrians.

The other choices either suggest unrestricted placement or incorrect areas, which could lead to potential hazards due to impaired visibility. For instance, putting stickers anywhere on the windshield could obstruct the driver's field of vision, leading to a greater risk of accidents. Similarly, placing signs on the rear window or side windows does not comply with regulations focused on the windshield's clear view area.