Which of the following is a requirement when operating a scaffold?

In the context of scaffold safety and regulations, the requirement that a scaffold must be able to support at least four times the intended load is crucial for ensuring the safety and stability of the structure. This requirement is based on engineering principles that take into account not only the weight of the materials and workers but also any additional factors such as dynamic loads that may occur during use, like wind or movements. By requiring a safety factor of four, it significantly reduces the risk of failure, which can lead to accidents, injuries, or fatalities on construction sites. This overload capacity is a standard practice in the construction industry to enhance safety measures, thus making it the correct answer in this context.

The other options do not align with scaffold safety regulations. Positioning scaffolds under trees can present risks of falling branches or debris. Covering scaffolds with plastic sheeting may obstruct visibility or ventilation and is not a standard safety requirement. Additionally, while bright colors may improve visibility, they are not mandated for safety and do not provide structural integrity or safety assurance.