Which sobriety test assesses the driver's ability to maintain focus and balance?

The walk-and-turn test is designed to assess a driver's ability to maintain focus and balance while performing a series of walking tasks. This test requires the individual to take a series of heel-to-toe steps along a straight line, turn on a designated mark, and then return in the same manner. It evaluates both cognitive and physical coordination, as the driver must concentrate on the task while also maintaining stability and balance. Any inability to follow instructions, missteps, or loss of balance can indicate impairment due to alcohol or drugs.

The other tests serve different purposes: the one-leg stand test focuses specifically on the individual’s balance, requiring them to stand on one leg for a period, while the field breathalyzer measures blood alcohol content. The finger-to-nose test evaluates motor skills and coordination, but it does not specifically focus on balance in the same way that the walk-and-turn test does. Thus, the primary emphasis of the walk-and-turn test makes it the correct choice for assessing a driver's ability to maintain focus and balance.