Which class of fire involves combustible metals such as sodium and magnesium?

The correct classification for fires involving combustible metals like sodium and magnesium is Class D. This class of fire is specifically designated for instances where reactive metals ignite, which requires specialized extinguishing agents that can handle the unique behavior of these materials when they burn. Class D fires burn at very high temperatures and can react with water or other chemicals in dangerous ways, making it crucial for responders to utilize the right type of fire extinguishing methods. The characteristics of combustible metals differ significantly from those of other materials found in the other classes of fire, thus necessitating a distinct approach in tackling these situations.