Red Seal Plumbing Exam 2025 – 400 Free Practice Questions to Pass the Test

The other options, B, C, and D, are incorrect because they do not fall into the category of "solid expansion control devices". B is incorrect because thermal couplers are used to monitor temperature, not control expansion. C is incorrect because hydraulic valves are used to control the flow of liquid, not expansion. D is incorrect because pressure sensors are used to measure pressure, not control expansion. Only option A, rod and tube and liquid bulb, are considered solid expansion control devices because they are designed specifically to control the expansion of materials in a solid state.