Which statement is true about the causes of vehicle fires?

The statement about poor trailer ventilation being able to cause flammable cargo to catch fire is accurate. Proper ventilation in trailers is crucial, especially when transporting flammable materials. Without adequate ventilation, heat can build up inside the trailer, which may ignite flammable vapors or substances. This emphasizes the importance of monitoring cargo conditions and ensuring that ventilation systems function correctly to prevent such dangerous situations.

In contrast, vehicle fires are not typically linked to design flaws as a primary cause, and while electrical failures can contribute to fires, they are not the sole cause. Additionally, fuel leaks are dangerous and cannot be considered harmless to cargo, as they pose a significant risk of ignition and explosion in the presence of an ignition source.