Final answer:
The correct finding that requires notifying the registered nurse in a client with cancer undergoing morphine sulfate therapy and showing signs of overdose is D. Decreased level of consciousness.
Step-by-step explanation:
If a client being administered morphine sulfate is exhibiting signs of an overdose, it is critical to notify the registered nurse immediately. Among the listed findings, Decreased level of consciousness should raise significant concern for a morphine overdose. Morphine is a potent opioid that can cause respiratory depression, ultimately leading to a decrease in the level of consciousness as the body's intake of oxygen reduces. Other signs of morphine overdose include pinpoint pupils, significantly decreased respiratory rate, and decreased blood pressure. It is less likely for a patient experiencing an opioid overdose to exhibit symptoms like increased respiratory rate or dilated pupils, which are not typical of opioid toxicity. Therefore, the correct answer would be D. Decreased level of consciousness.