You observe a small plaque on an electrical appliance that reads, in part, "115 volts ac 60 hz." this means that the appliance a. contains a heating element. b. may be operated with batteries. c. produces special safety hazards. d. must be operated on alternating current.

You observe a small plaque on an electrical appliance that reads, in part, "115 volts AC 60 Hz." AC stands for alternating current. This means that the appliance must be operated on alternating current. Electrical appliance based upon their power consumption can be supplied on direct current (DC) or alternating current (AC).  In this case, the appliance must be supplied on AC current.

Don’t know sorry if i know it later i would put it here

Which approach what do you mean