In the past, users brought personal laptops to the office to bypass some of the security protocols on their desktops. Due to new security initiatives, management has asked that users not be allowed to attach personal devices to the network. Which of the following should a technician use to BEST meet this goal? 

Answer options:

A. Shut down unused ports on switches
B. Upgrade firmware on network devices
C. Allow only secure protocols on the network
D. Disable unnecessary services

C