Which of the following gases emitted from automobile exhaust is poisonous?

Option 1 : Carbon monoxide

Option 1 is correct, i.e. Carbon monoxide.

• Carbon monoxide gas emitted from automobile exhaust is poisonous.
• Carbon monoxide (CO) is slightly less dense, colorless, odorless, and tasteless gas than oxygen.
• It is toxic to animals and humans of hemoglobin when found in concentrations above about 35 parts-per notation, "although it is also developed in small amounts in normal animal metabolism and is assumed to have some natural biological functions.
• This gas affects the oxygen capacity of Red Blood Cells.