The correct answer is C. Phenobarbital is used to control seizures . Phenobarbital is also used to relieve anxiety. It also used to prevent withdrawal symptoms I people who are dependent (addicted) on another barbiturate medication and are going to stop taking the medication. It is in a class of medication called barbiturates and works by slowing activity in the brain. The directions of a physician or doctor in taking the medication must be followed. If taken for a long time, it may not control symptoms as well as it did at the beginning of treatment. A person must keep their doctor updated on how they are feeling during treatment.