A nurse is caring for a patient who has a peripheral IV saline lock in place but is not currently receiving a continuous infusion. Which action best maintains the patency of the saline lock?

Flush the IV with heparin instead of saline

Leave the IV catheter open to air when not in use to prevent pressure build-up.

Flush the IV catheter with saline before and after medication administration and every 8 to 12 hours when not in use.

Clamp the IV tubing after each medication administration without flushing.