Final answer:
The nurse should assess the patency of the IV line to determine why the client has only received 80 mL over the last 2 hours.
Step-by-step explanation:
The nurse should take action A, which is to assess the patency of the IV line. This means checking whether the IV line is clear and allowing the fluid to flow properly. The nurse should check for any kinks, occlusions, or other issues that may be preventing the infusion from flowing at the desired rate. By assessing the IV line, the nurse can identify and address any problems that may be causing the slow infusion rate.