Final answer:
The nurse administering donepezil to a client with Alzheimer's disease should report a new onset of muscle cramps immediately to the healthcare provider as it may signal a serious reaction to the medication.
Step-by-step explanation:
The question is focused on the administration of donepezil to a client with Alzheimer's disease and which finding should be reported to the healthcare provider immediately. Of the provided options, (a) mild nausea is a common side effect of donepezil and while it should be monitored, it is not typically urgent. (b) A blood pressure of 140/90 mmHg is considered high but may not be urgently alarming without other symptoms. (d) A heart rate of 90 beats per minute is within normal limits. However, (c) a new onset of muscle cramps should be reported immediately as it could be indicative of a more serious reaction to the medication, such as rhabdomyolysis or an electrolyte imbalance, which requires prompt attention. Therefore, the new onset of muscle cramps is the finding the nurse should report to the provider immediately.