Final answer:
The method used to prevent access to USB ports to stop employees from copying data is USB lockdown software, which controls USB access and helps to secure sensitive information.
Step-by-step explanation:
The method employed by some organizations to prevent access to USB ports in order to keep employees from copying data is c) USB lockdown software. This software allows administrators to control USB access on company computers and prevent the unauthorized transfer of sensitive information. It is an aspect of endpoint security measures organizations can implement to protect against data breaches and misuse of company resources. Unlike a firewall, which is designed to block unauthorized access to or from a private network, or encryption, which secures data by converting it into a coded form, USB lockdown software specifically targets the use of USB ports to prevent unauthorized data transfer.