Which of the following is a common boiler fuel?

Natural gas is a common boiler fuel due to its efficiency, availability, and cleaner-burning properties compared to other fossil fuels. It is used in many industrial and residential heating systems as it can be easily transported through pipelines and burns at a high temperature, providing effective steam generation.

While wood shavings might also be used as a biomass fuel in specific types of boilers, they are not as widely utilized as natural gas in the broader context of boiler operations. Hydraulic fluid is primarily used for lubricating machinery and has no role in fuel combustion processes, while deionized water is utilized for steam generation rather than being a fuel itself. Thus, the effectiveness, practicality, and environmental considerations associated with natural gas make it a staple choice in boiler systems.