Which of the following combinations of clothing materials could increase the risk of injury during an electrical arc?

The combination of polyester and spandex significantly increases the risk of injury during an electrical arc due to the properties of these materials. Polyester is a synthetic fabric that can melt under high heat, such as that generated during an electrical arc. When polyester melts, it can stick to the skin, causing severe burns. Similarly, spandex, while stretchy, is also a synthetic material that does not provide the necessary protective qualities against heat and electrical hazards.

In contrast, the other fabric combinations tend to either be more fire-resistant or made from natural fibers that do not melt. For example, cotton and wool have more favorable characteristics for protective clothing because they have better flame resistance compared to synthetic materials. Therefore, wearing clothing made of polyester and spandex poses a higher risk for linemen who may encounter electrical arcs, making this combination particularly hazardous.