Which of the following would allow separation between the Internet and the internal network of a company?

Virtual Local Area Networks (vLANs) enable the logical segregation of a network into distinct broadcast domains, even on the same physical infrastructure. By assigning internet-facing services to one vLAN and internal company resources to another, firewalls can then be used to strictly control traffic flow between these logically separated networks and the internet, thus achieving effective separation.

Reviewing audit logs is a security monitoring activity, not a mechanism for network separation.

Reviewing system logs is a troubleshooting and monitoring activity, not a mechanism for network separation.

A Demilitarized Zone (DMZ) is a network segment that provides a layer of security between an organization's internal network and an external network, typically the Internet. While a DMZ uses network separation techniques, vLANs themselves are the underlying technology that allows for such segmentation.