Dirty headlights can cut your night vision by __________.

Dirty headlights significantly diminish the amount of light they emit, which can greatly impair your visibility during nighttime driving. Studies have shown that when headlights are not clean, their effectiveness is reduced, and the light they project onto the road can be severely compromised.

The assertion that dirty headlights can cut your night vision by one-half reflects the considerable reduction in visibility that can occur due to grime, dirt, and other buildup on the lenses. When headlights are only able to provide half the illumination they are designed for, it can drastically limit a driver's ability to see and react to obstacles, road signs, and other vehicles. Maintaining clean headlights is crucial for safe driving, particularly at night or in low-visibility conditions.

The other options suggest greater reductions, which tend to exaggerate the impact that dirty headlights have compared to the well-documented figure that indicates a one-half reduction. Hence, one-half is a realistic and widely recognized estimation of how much dirty headlights can impair night vision.