During cranking, what happens to CO levels with improper air temperature?

During engine cranking, the air temperature plays a crucial role in the combustion process. If the air temperature is improper—particularly if it is too low—it can lead to inefficient combustion. Cold air is denser and contains more oxygen, which can cause an imbalance in the air-fuel mixture, resulting in incomplete combustion. This often leads to an increase in carbon monoxide (CO) levels as more unburned fuel is emitted due to the insufficient combustion conditions.

The correct choice indicates that CO increases under these circumstances, reflecting the impact of improper air temperature on the efficiency of the combustion process during engine cranking. Elevated CO levels are a direct consequence of this phenomenon, as the engine struggles to achieve the optimal combustion temperature and ratio, thus generating more carbon monoxide as a byproduct.