An organization has recently experienced unauthorized device access to its network. To proactively manage the problem and mitigate this risk, the BEST preventive control would be to: 

Answer options:

A. keep an inventory of network and hardware addresses of all systems connected to the network.
B. install a stateful inspection firewall to prevent unauthorized network traffic.
C. implement network-level authentication and login to regulate access of devices to the network.
D. deploy an automated asset inventory discovery tool to identify devices that access the network.

C