A technician must install and configure a network device in a building with 20 classrooms. Each room must be on a separate subnet and should not be able to see traffic from other subnets. Which of the following is the MOST cost-effective solution? 

Answer options:

A. A switch with VLANs created for each segment
B. A router with interfaces connected to a switch in each room
C. A VoIP endpoint connected to a hub for each network
D. A firewall with DHCP pools for each subnet

A