Final answer:
The term that best describes the action of instituting a new central line care protocol to prevent site infection after it has been shown to be significantly more effective than previous approaches is implementation.
Step-by-step explanation:
The term that best describes the action of instituting a new central line care protocol to prevent site infection after it has been shown to be significantly more effective than previous approaches is implementation. In this case, the new protocol is being put into practice and applied in healthcare settings to reduce the risk of infections associated with central lines. The implementation of the new protocol involves following a checklist of steps, ensuring proper aseptic technique, sterilization protocols, and maintaining a sterile field.