A network engineer is asked to connect two customer sites using Layer 2 connectivity over an
MPLS backbone. One customer site uses PPP connectivity with the service provider and the other
customer site uses Frame Relay connectivity with the service provider. Which option can the
network engineer use to enable network connectivity between these two customer sites?

A.
GRE tunnels

B.
IP interworking

C.
Ethernet interworking

D.
L2TPv3 tunnels