Final answer:
The nurse should include the priority instruction of 'Do not submerge your pacemaker, take only showers.' in the client's discharge teaching.
Step-by-step explanation:
The nurse should include the priority instruction of 'Do not submerge your pacemaker, take only showers.' in the client's discharge teaching. This is because pacemakers are electronic devices that can be damaged by water. Taking showers instead of baths or submerging the pacemaker in water helps prevent damage to the device. Other instructions may also be important, but this is the priority instruction for the client's safety and the proper functioning of the pacemaker.