Two switches, S1 and S2, are connected to each other. To realize segmentation and greater security, each switch has three VLANs configured (students, faculty, and IT). When a faculty endpoint connected to S1 communicates with a faculty endpoint connected to S2, how does S2 know the message belongs to the faculty VLAN?
a. S1 tags the message, indicating it belongs to the faculty VLAN when sending it to S2.
b. A logical VPN implemented between the two switches tags the message when sending it.
c. S1 uses the vendor-neutral IEEE 802.11 protocol to tag the message when sending it to S2.
d. A router needs to be used between the switches to ensure successful delivery of VLAN messages.