Final answer:
The nurse should assess the client's pain level and provide appropriate pain management as the first priority when a male client is moaning after a colon resection for colon cancer.
Step-by-step explanation:
When a male client is moaning after a colon resection for colon cancer, the nurse should implement the intervention of assessing the client's pain level and providing appropriate pain management as the first priority. It is important to assess if the client is experiencing any complications such as infection or bleeding that may be causing the moaning. The nurse can administer pain medication as prescribed, provide comfort measures, and monitor the client's vital signs and surgical site for any signs of complications.