Which of the following is the BEST method to mitigate security risk within the environment?

Company A and Company B both supply contractual services to a fast paced and growing auto
parts manufacturer with a small local Area Network (LAN) at its local site. Company A performs inhouse billing and invoices services for the local auto parts manufactacturer. Company B provides
in-house parts and widgets services for the local auto parts manufacturers. Which of the following
is the BEST method to mitigate security risk within the environment?

A.
Virtual Private Network

B.
Role-Based access

C.
Network segmentation

D.
Public Key Infrastructure