Final answer:
b) 1 inch. The minimum size of the pipes connecting the boiler to the water column depends on the flow rate and pressure of the system. However, in general, 1 inch pipes are commonly used for residential boiler systems.
Step-by-step explanation:
The minimum size of the pipes connecting the boiler to the water column depends on the flow rate and pressure of the system. Without additional information, it is difficult to determine the exact minimum size. However, in general, 1 inch pipes are commonly used for residential boiler systems, while larger systems may require 1.5 inch or 2 inch pipes for sufficient water flow.