Which of the following materials is considered not fire resistant?

Synthetic materials are generally considered less fire resistant compared to natural fibers, cotton, or leather. This is because many synthetic materials are made from petroleum-based products, which can ignite easily and burn rapidly when exposed to flame. Additionally, they may emit toxic fumes as they burn, adding to their hazards in a fire scenario.

In contrast, natural fibers like cotton and wool possess some inherent fire-resistant properties, as they typically have higher ignition temperatures and burn more slowly than synthetic options. Leather also offers a degree of fire resistance due to its density and moisture content, which can help slow down the propagation of flames. Therefore, while all materials have varying degrees of fire resistance, synthetic materials are more likely to be identified as not fire resistant in a comparative context.