Which of the following is known as a quiet killer?

Explanation

Carbon monoxide (CO) is known as the "silent" or "quiet killer" because it is a colorless, odorless gas that is highly toxic to humans and animals. It is produced by incomplete combustion of carbon-containing fuels such as wood, gasoline, natural gas, and coal. CO binds to hemoglobin in the blood much more readily than oxygen does, forming carboxyhemoglobin. This reduces the blood's ability to carry oxygen, leading to tissue hypoxia (oxygen deficiency) and, in severe cases, death.