Which seasonal factors are commonly associated with carbon monoxide poisoning?

The correct choice is associated with the increased risk of carbon monoxide (CO) poisoning during the winter months due to several important factors. In winter, many people use space heaters to provide additional warmth. These heaters—especially when improperly vented or used in enclosed spaces—can produce harmful levels of carbon monoxide. Moreover, this season is often associated with vehicles being left running in garages, which can lead to CO buildup in enclosed spaces and pose lethal risks. The mention of "garage suicide" refers to instances where individuals may leave a vehicle running in a garage, thus causing fatal carbon monoxide exposure.

On the other hand, while other seasons can have certain risks, they are not as directly linked to carbon monoxide poisoning in the same way. For instance, summer typically involves outdoor activities where the risk of CO is lower, and spring allergies or failures of air conditioning systems do not primarily contribute to increased CO levels. Similarly, fall is associated with ventilation issues, but those risks are not as pronounced and specific as the hazards posed during winter months with space heaters and enclosed vehicles.