Which of the following is a potential hazard to fuel supply containers?

Direct sunlight exposure is identified as a potential hazard to fuel supply containers because prolonged exposure to UV rays can damage the materials used in the containers. This degradation can lead to deterioration, such as weakening of the structural integrity or even melting in the case of certain plastics. Additionally, sunlight can raise the temperature of the container, potentially leading to pressure build-up or even the risk of thermal expansion of the fuel inside, which can be hazardous.

In contrast to direct sunlight exposure, the other options may not pose the same immediate risk to the integrity of fuel supply containers. Overcharging the fuel can lead to pressure-related issues but is less about the container itself and more about operational safety surrounding refueling practices. Low fuel pressure generally pertains to the system's operation rather than directly affecting the container's safety, while cold temperatures usually tend to affect the fuel's performance rather than physically compromising the container. Thus, the focus on direct sunlight helps clarify the specific risks associated with environmental factors affecting fuel containers.