Which of the following is NOT a class of fire?

In fire safety classifications, different classes of fires are defined based on the materials that are burning. Class A fires involve ordinary combustibles such as wood, paper, and cloth. Class B fires involve flammable liquids and gases. Class C fires are those that involve energized electrical equipment. Class K fires typically arise from cooking oils and fats, which are common in commercial kitchens.

Class X is not recognized as an official category of fire classification in standard fire safety terminology. Therefore, identifying Class X as a non-existent class of fire is accurate and reflects an understanding of the established categories used by fire safety professionals. This also highlights the importance of being familiar with recognized classifications, as they dictate the types of extinguishing agents that should be used for each class to effectively combat fires safely and efficiently.