What should a driver remove to improve vision before entering a tunnel?

Removing sunglasses before entering a tunnel enhances vision because sunglasses are designed to reduce glare and brightness in sunlight. When transitioning from bright outdoor conditions to the darker environment of a tunnel, wearing sunglasses can significantly impede a driver's ability to see clearly due to the sudden contrast in lighting.

In tunnels, adequate visibility is crucial for safe driving, as the lack of natural light can make it difficult to notice obstacles, traffic signals, or the behavior of other road users. By taking off sunglasses, a driver allows their eyes to adjust to the lower light levels, thus improving overall visibility and reaction time within the tunnel.

The other options, while they may influence comfort and peripheral vision, do not have the same direct impact on visibility in the contrast of lighting that entering a tunnel presents.