A company's security team recently discovered a number of workstations that are at the end of life. The workstation vendor informs the team that the product is no longer supported, and patches are no longer available. The company is not prepared to cease its use of these workstations. Which of the following would be the BEST method to protect these workstations from threats?

A. Deploy whitelisting to the identified workstations to limit the attack surface.
B. Determine the system process criticality and document it.
C. Isolate the workstations and air gap them when it is feasible.
D. Increase security monitoring on the workstations.