Pick the incorrect statement (ozone thickness, 2-stroke vs 4-stroke emissions, mercury toxicity) From the following, identify the statement that is wrong based on established environmental and engine-emission facts.

Introduction / Context:
This item mixes atmospheric science and engine-emissions knowledge. The goal is to spot the incorrect claim among statements about polar ozone depletion, two-stroke engine emissions, and mercury health effects. Accurate classification is essential for air quality management and public health.

Given Data / Assumptions:

• Two-stroke spark-ignition engines typically run with fuel-oil mix and exhibit scavenging losses.
• Four-stroke engines generally burn fuel more completely, with less short-circuiting.
• Polar ozone loss is associated with cold stratospheric conditions enabling heterogeneous chlorine chemistry.
• Minamata disease is mercury poisoning with severe neurological effects.

Concept / Approach:
Two-stroke petrol engines usually emit higher unburned hydrocarbons and often higher CO due to short-circuiting of fresh charge and richer mixtures. Therefore, the assertion that their CO is “much less” than four-stroke engines is wrong. The other statements are broadly consistent with fundamentals: polar ozone thinning is linked to extremely cold stratospheric temperatures that form polar stratospheric clouds, and mercury indeed causes Minamata disease.

Step-by-Step Solution:

Verification / Alternative check:
Emission inventories and dynamometer tests show two-strokes often exceed four-strokes in CO and HC emissions when uncontrolled, validating the choice.

Why Other Options Are Wrong:

Common Pitfalls:
Over-interpreting (a) as the sole cause; chemistry involving chlorine/bromine is the mechanistic driver, with cold conditions enabling it.

Final Answer:
Carbon monoxide present in the two stroke petrol engine exhaust is much less as compared to that emitted from a four stroke engine.