What types of safety devices are commonly used in scaffolding?

The correct answer identifies safety devices specifically designed for scaffolding environments, which are crucial for preventing falls and ensuring worker safety on elevated platforms. Safety harnesses are personal protective equipment that secures a worker to prevent a fall from height. Guardrails provide a physical barrier around the scaffolding, helping to prevent falls by keeping workers safe from the edges. Warning lines serve as visual alerts to indicate hazardous areas, guiding workers and reminding them of the risks associated with working on scaffolds.

In contrast, the other options mention safety equipment that, while important, are not specifically tailored to the unique risks presented by scaffold work. Hard hats and gloves are general safety items, relevant to various construction tasks but not exclusively tied to scaffolding operations. Emergency ladders and helmets offer vital support in general construction and rescue scenarios, yet do not specifically address the scaffolding context. Rescue devices and reflective vests enhance overall safety on construction sites but do not directly align with the specific safety measures needed for working on scaffolding structures.