Which of the following can be used as a substitute for a 2A rated fire extinguisher?

A 55-gallon drum of water with fire pails is an effective substitute for a 2A rated fire extinguisher due to the nature of the fire it is intended to combat. The 2A rating specifically indicates the extinguisher is suitable for tackling fires involving ordinary combustibles such as wood, paper, and cloth. Water is an effective agent for extinguishing these types of fires as it cools the burning materials and eliminates the heat component necessary for combustion.

Using a drum of water allows for a significant volume that can be poured or used with pails to douse flames effectively. The combination of a substantial water supply and the capability to manage fire pails makes this option suitable in the absence of a 2A rated extinguisher. Other options, while useful in certain contexts, do not provide the same level of effectiveness for controlling ordinary combustible fires.