Which of the following items are used as an additional safety precaution in case lights burn out or are broken?

Reflectors are used as an additional safety precaution to enhance visibility, especially in situations where lights are not functioning properly due to burnout or damage. They are designed to reflect light from other vehicles, increasing the chances of being seen by approaching drivers. This is particularly important for ensuring safety on roadways, construction sites, or any areas where equipment operation is taking place.

In contrast, while flares, warning flags, and flashlights can serve important safety functions, they are typically used in different contexts. Flares are used for signaling and directing traffic but do not provide a continuous indication of the presence of an object or area like reflectors do. Warning flags are often used to indicate hazards or direct traffic in a more manual fashion, but they do not provide any reflective properties. Flashlights can aid visibility and communication in dark areas but are not stationary solutions for ongoing hazards like reflectors. Thus, reflectors are the most appropriate choice for providing an additional safety precaution in the specific scenario of light failure.