A driver's reaction time can be altered at 0.02-0.05% blood alcohol content, depending on the person. On average, 1 standard drink (either 12 fl. oz of beer with 5% alcohol, 8-9 fl. oz of liquor with 7% alcohol, 5 fl. oz of wine with 12% alcohol, or 1.5 fl. oz of distilled hard liquor with 40% alcohol), can raise blood alcohol content to 0.02%-0.05% effectively decreasing a driver's reaction time. The correct answer is one drink can alter a driver's reaction time.