Final answer:
The minimum pipe size for the siphon connected to each steam gauge should be 1/2 inch.
Step-by-step explanation:
The question states that each steam gauge must be connected to a valve with a tee or lever. When the valve is open, the handle should be parallel to the pipe. Additionally, the steam gauge must be connected to at least a 1/2 inch siphon pipe. This means that the minimum pipe size for the siphon is option b) 1/2 inch.