Final answer:
The nurse's priority is to report the respiratory rate of 12 breaths/min to the provider as morphine can cause life-threatening respiratory depression.
Step-by-step explanation:
The nurse's priority finding to report to the provider after a client receives morphine IV for pain relief would be A. Respiratory rate of 12 breaths/min. Morphine can lead to respiratory depression, which is potentially life-threatening. Given that the normal respiratory rate for adults ranges from 12 to 20 breaths per minute, a rate of 12 is on the lower end of the normal range; however, in the context of opioid administration, it would be essential to monitor for any further decrease. The other options, such as decreased bowel sounds, blood pressure of 110/70 mm Hg, and urinary output of 50 mL/hour, while important to note and manage, are not as immediately life-threatening as respiratory depression.