The correct answer is (a) Potassium bromide.
Potassium bromide is a medication used to treat seizures, anxiety, and insomnia. It is also used to treat certain types of heart arrhythmias. Potassium bromide is a sedative-hypnotic drug, which means it slows down the central nervous system and causes drowsiness. It is available as a tablet, capsule, or liquid.
Calcium chloride is a mineral that is used to treat low blood calcium levels. It is also used to treat certain types of muscle cramps and spasms. Calcium chloride is available as an injection or as a pill.
Ethyl alcohol is a depressant that is used to treat alcohol withdrawal symptoms. It is also used as a solvent and as a fuel. Ethyl alcohol is available as a beverage or as a topical medication.
Phosphorus trichloride is a toxic chemical that is used to make pesticides and other chemicals. It is not used as a medication.
Potassium bromide is the only option that is used as a sedative.