How do protocols such as ATM and Frame-Relay support differentiating multiple customers or traffic types on the same physical wire?

How do protocols such as ATM and Frame-Relay support differentiating multiple customers or traffic types on the same physical wire?
A . ATM and Frame-Relay are circuit switched protocols and use Virtual Circuits to create logical separation of traffic.
B . ATM and Frame-Relay are point-to-point protocols and do not support different customers or traffic type on the same physical wire.
C . ATM and Frame-Relay are circuit switched protocols and use VLAN’s to create logical separation of traffic.
D . ATM and Frame-Relay are circuit switched protocols and use IP Header information to create logical separation of traffic.

Answer: A