What is the primary fuel for a Class B fire?

Class B fires specifically involve flammable liquids, oils, and greases. These types of fires can occur in various environments, such as kitchens, garages, and workplaces where combustible liquids are present. The primary characteristic that defines a Class B fire is the type of fuel involved, which is why the correct answer focuses on those flammable substances.

Using the right extinguisher and techniques is crucial for effectively combating a Class B fire. Class B fire extinguishers are typically labeled with a red square containing a flame symbol and are designed to smother the flames rather than using water, which can exacerbate the situation or spread the fire due to the flammable nature of the substances involved. Understanding this classification helps in selecting the appropriate safety measures and firefighting strategies in an emergency.