Final answer:
Bushings can be used on gas piping only for the purpose of reducing sizes; they are not meant for any other applications in gas piping to ensure safety and proper function.
Step-by-step explanation:
The question, "Can bushings be used on gas piping?" addresses a topic in the realm of plumbing or gas fitting, which is related to engineering practices. When it comes to using bushings on gas piping, the correct answer is: b) Yes, but only for reducing sizes. It is important to note that while bushings can be used on gas piping, they are specifically crafted for the purpose of reducing the size of the pipe. Therefore, they are not suitable for every application and have a particular restriction to ensure the safety and functionality of the gas piping system.