Which Metro Ethernet technology uses a minimum of resources from the service provider network?

Refer to the exhibit.

A retail company has around 500 branches across the U.S. The company is connected to the DC and DR routers through a Frame Relay cloud. All the communication happens only between BR routers to DC or DR routers, and there is no BR router to BR rotter communication. The service provider has decided to discontinue the Frame Relay service and replace it with Metro Ethernet. The retail company currently uses OSPF NBMA mode as IGP, which is the only scenario that the IT team is familiar with. The retail company decides to optimize the data center computing resources with server virtualisation. They have many serve, segments that need Layer 2 connectivity between the DC router and me DR router tor VM failover.

Which Metro Ethernet technology uses a minimum of resources from the service provider network?
A . EVPL
B . Provider backbone bridge
C . VPLS
D . QinQ

Answer: B