Final answer:
The nurse should implement intervention a. Prepare to insert a pacemaker first for a client in complete heart block.
Step-by-step explanation:
The nurse should implement intervention a. Prepare to insert a pacemaker first for a client in complete heart block. Complete heart block results in a complete dissociation of the atria and ventricles, and the AV node becomes the primary pacemaker. A pacemaker is necessary to establish a normal heart rate and ensure effective blood pumping.