Final answer:
The correct action if a mercury thermostat is out of adjustment is to adjust the mercury tilt switch carefully. Shaking or disposing of it immediately is not appropriate, and ignoring the problem won't solve it.
Step-by-step explanation:
If a mercury thermostat seems out of adjustment, the first thing to do is c) Adjust the mercury tilt switch. It's important to handle mercury devices with care due to the toxic properties of mercury. Shaking it vigorously could potentially damage the thermostat or cause a mercury spill, which would be hazardous. Disposing of it immediately isn't necessary unless the device is broken and mercury exposure is a risk. Ignoring the problem is not advisable as it will not correct the temperature regulation issue. Properly adjusting the mercury tilt switch can recalibrate the thermostat to function correctly. Before attempting any adjustment, make sure to consult the thermostat's instruction manual or seek professional assistance if you are unsure of how to proceed.