What statement is true concerning a one-pipe hydronic heating system?

Correct Answer: Option C — Each heating coil inlet temperature is different, as the hot water inlet temperature to each heating coil progressively drops as the water passes through each successive series-connected coil.

In a one-pipe hydronic system, water flows in a single loop through successive heating coils. As the water releases heat to each coil, its temperature progressively drops. Consequently, each downstream coil receives water at a lower temperature than the previous one, resulting in varying inlet temperatures throughout the system.