Which hazard class identifies substances that are flammable?

The correct answer identifies Hazard Class Number 3, which comprises flammable liquids. Substances in this category are characterized by their ability to ignite easily and sustain combustion at relatively low temperatures. These materials pose significant risks during transport and storage, necessitating rigorous safety measures and appropriate handling practices to mitigate fire hazards.

Hazard Class Number 1 pertains to explosive materials, which are defined by their potential to detonate or produce a violent reaction. Hazard Class Number 6 includes toxic substances, which can pose a poisoning risk rather than a fire risk. Hazard Class Number 5 comprises oxidizers, which can enhance the combustion of other materials but are not themselves classified as flammable. Understanding the specific hazards associated with each class is critical for the safe management of hazardous materials.