The correct answer is (d) Sarin gas.
Sarin is a colorless, odorless, and tasteless liquid that is highly toxic to humans and animals. It is a nerve agent that can cause death within minutes of exposure. Sarin was first developed in Germany in the 1930s and was used as a chemical weapon in the Syrian civil war.
Mustard gas is a blistering agent that can cause severe burns to the skin, eyes, and respiratory system. It was first used in World War I and has been used in several conflicts since then.
Chlorine gas is a greenish-yellow gas that is used as a disinfectant and bleaching agent. It is also a chemical weapon that can cause respiratory problems, skin burns, and death.
Methyl isocyanide gas is a colorless, flammable gas that is used in the production of pesticides and plastics. It is a chemical weapon that can cause respiratory problems, skin burns, and death.
Sarin gas is the most deadly of the four chemical agents listed. It is a nerve agent that can cause death within minutes of exposure. Mustard gas, chlorine gas, and methyl isocyanide gas are all toxic, but they are not as deadly as sarin gas.