Which statement is true about the operation of Layer 2 VPNs?

Which statement is true about the operation of Layer 2 VPNs?

A.
Layer 2 VPNs require that CE devices use the same Layer 2 encapsulation

B.
Layer 2 VPNs do not permit CE devices to operate a Layer 3 protocol with each other

C.
Service provider routers must evaluate the IP header of packets as they traverse their network

D.
Layer 2 VPNs allow CEs to use different encapsulations on either side of the VPN