Which of the following is a CNS stimulant commonly used to treat ADHD?

Ritalin is a central nervous system (CNS) stimulant that is widely used to treat Attention Deficit Hyperactivity Disorder (ADHD). Its active ingredient, methylphenidate, helps to increase attention and decrease impulsiveness and hyperactivity in patients diagnosed with ADHD. This specific mechanism of action is what makes it effective for individuals who have difficulty focusing or controlling their behavior due to this condition.

Other options listed do not serve the same purpose. Ambien is primarily used as a sleep aid for insomnia, Doriden is an older sedative and not used for ADHD, and Placidyl is another sedative that also does not address the symptoms of ADHD. Each of these alternatives works on different receptors in the brain and is intended for different medical issues, rather than the regulatory focus on attention and hyperactivity seen with Ritalin.