What types of fire extinguishers must be included in the installation?

The requirement for fire extinguishers in installations involving flame effects is specifically outlined in safety standards to ensure effective fire response capabilities. The correct choice emphasizes the necessity of having multiple types of extinguishers that can combat various classes of fires that may arise from flame effects.

Type A extinguishers are effective against ordinary combustibles such as wood, paper, and cloth, which may be present in stage environments. The inclusion of at least two Type A extinguishers ensures readiness for fires involving these materials. Additionally, Type B extinguishers are essential for flammable liquids, gases, and greases commonly found in theatrical settings. The specification of two 10-B:C extinguishers ensures that there is adequate coverage for fires involving these materials and also provides protection against electrical fires, as the "C" designation indicates suitability for electrical fires.

This selection reflects a comprehensive safety approach, ensuring that the installation is equipped to handle a range of fire emergencies effectively. Therefore, having at least two Type A extinguishers and two 10-B:C extinguishers creates a robust fire safety strategy appropriate for environments using flame effects before an audience.