This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to install a digital thermostat
Purchase a digital thermostat from a home improvement or hardware store.
Turn off the power to your furnace before beginning digital thermostat installation.
Remove the cover of the old thermostat.

Choose from: a). Remove the unit's screw-on cover. W2d appliance models normally have 2 screws on the base side and 4 screws on the side.; b). Set your thermostat on the circuit breaker (next to the furnace). Pull the plug out of the unit and remove the cover from the new thermostat.; c). ( the exception to this rule is the temperature meter. ) Insert the power cord into the thermostat housing.; d). Most of them simply pop off easily with a little force. Remove the screws from the screw terminals in the sub-base of the old thermostat and remove it from the wall.;
The answer is:
d).