computer networking

please answer fast

Which of the following actions correspond to SDN approach? ) A router exchanges messages with another router, indicating the cost for it (the sending router) to reach a destination host. B All routers in the network send information about their incoming and outgoing links to a logically centralized controller. All routers send information about their incoming and outgoing links to other routers in the network. All routers in the network perform routing algorithms and generate routing table