Pick the incorrect statement about CO control and sources in ambient air Identify the wrong assertion concerning catalytic converters, CO toxicity, petrol exhaust composition, and natural CO sources.

Introduction / Context:
Automotive emissions and atmospheric carbon monoxide (CO) have well-documented sources and controls. This question checks familiarity with what three-way catalytic converters target, CO health effects, typical petrol exhaust composition, and natural background sources of CO.

Given Data / Assumptions:

• Modern gasoline vehicles use catalytic converters to reduce CO, HC, and NOx.
• CO is toxic because it binds to hemoglobin, impairing oxygen transport.
• Petrol (gasoline) has low sulphur content, especially with modern fuel standards.

Concept / Approach:
Among the options, the incorrect claim is that SO₂ is the main pollutant in petrol exhaust. The dominant pollutants are CO, unburned hydrocarbons, and NOx; SO₂ is typically minor due to low sulphur levels in gasoline. The other statements are correct: catalytic converters reduce CO; CO can cause fatal asphyxiation; and biogenic/photochemical processes (including oxidation of organics) contribute to background CO.

Step-by-Step Solution:

Verification / Alternative check:
Emission standards and inventories consistently list CO and HC as the primary gasoline-exhaust concerns; SO₂ emissions primarily track fuel sulphur content and are far lower for petrol than for high-sulphur fuels.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming SO₂ is major across all fuels; it depends strongly on sulphur content, which is tightly limited in gasoline.

Final Answer:
Sulphur dioxide is the main pollutant emitted from the exhaust of petrol driven automobiles.