Drivers were tested on various driving exercises before they had been drinking. They were given alcoholic beverages of their choice. _________________ occurred as BALs increased.

As blood alcohol levels (BALs) increase following the consumption of alcoholic beverages, a steady decline in driving ability is observed. This decline can affect a driver's reaction time, decision-making, hand-eye coordination, and overall motor skills. The impairment begins at low levels of alcohol consumption and becomes progressively worse as more alcohol is consumed.

Research consistently shows that even a small amount of alcohol can interfere with a person's ability to drive safely. As BAL levels rise, the cognitive and physical effects become more pronounced, leading to a significant degradation in driving performance. The relationship between alcohol consumption and driving ability is well-established, underlining why this option accurately reflects the impact of alcohol on drivers.

Other choices imply either minimal impairment or no impairment at all, which contradicts the extensive evidence regarding alcohol's effects on driving skills. The option referencing headaches does not relate to the immediate effects of alcohol on driving ability, further reinforcing why the correct answer highlights a clear trend of decline in necessary driving functions as alcohol consumption increases.