What is the lightest of the synthetic fibers, often used in water rescue situations because it does not absorb water?

The correct answer is polypropylene, which is indeed the lightest of the synthetic fibers listed and is often preferred in water rescue situations. Its unique properties include a very low density, making it lighter than other synthetic fibers. Unlike many materials that absorb water, polypropylene does not soak up moisture, which allows it to remain lightweight and buoyant when used in rescue applications. This characteristic is particularly beneficial in situations where minimizing weight is crucial for efficiency and safety in water rescues.

Nylon, while strong and durable, is heavier and does absorb water to some extent, which can add unnecessary weight during water rescue efforts. Polyester is also a common synthetic fiber used in various applications, but it typically has a higher density than polypropylene. Kevlar, known for its strength and heat resistance, is primarily used in ballistic and cut-resistant applications rather than water rescue, making it unsuitable in this context.