Correct Option: B

Tear gas, formally known as a lachrymatory agent or lachrymator (from lacrima meaning “tear” in Latin), is a non-lethal chemical weapon that stimulates the corneal nerves in the eyes to cause tears, pain, and even blindness. Common lachrymators include OC, CS, CR, CN (phenacyl chloride), nonivamide, bromoacetone, xylyl bromide and syn-propanethialS-oxide (from onions). Tear gas works by irritating mucous membranes in the eyes, nose, mouth and lungs, and causes crying, sneezing, coughing, difficulty breathing, pain in the eyes, temporary blindness, etc. Lachrymators are thought to act by attacking sulphydryl functional groups in enzymes. The compound 2-chlorobenzalmalononitrile (also called o-chlorobenzylidenemalononitrile) (chemical formula: C10H5ClN2), a cyanocarbon, is the defining component of a “tear gas” commonly referred to as CS gas, which is used as a riot control agent. CS gas is generally accepted as being non-lethal