Final answer:
Check near the water heater for the expansion tank, which is usually installed on the cold water line to absorb excess pressure. The correct answer is option b.
Step-by-step explanation:
When looking for an expansion tank in a plumbing system, the most common place to check would be near the water heater. Expansion tanks are typically installed on the cold water line close to the water heater to absorb excess pressure due to thermal expansion.
In some cases, where the plumbing system layout allows or requires it, the expansion tank could be located elsewhere, such as in the basement, if it is closer to the main water supply entry or if there is better support for the tank.
If you are unsure about the location or installation of an expansion tank, it would be wise to consult or call a professional. Professionals can provide a thorough inspection and ensure it is properly installed and functioning as intended. Remember, incorrect handling could lead to system damage or personal injury.