Which one of the following is an extremely short-lived and unstable air/water pollutant?

Volatile organic compounds are extremely short-lived and unstable air and water pollutants.

They evaporate quickly and react readily, so they do not linger long in one form.

Smog is a visible mixture of pollutants and a condition, not a single fleeting compound.

Persistent organic pollutants are by definition long-lasting, the very opposite of short-lived.

Polycyclic aromatic hydrocarbons are stable, persistent substances that resist breakdown.

Because they react fast in sunlight, volatile organic compounds help form photochemical smog.