Which of the following is a Path Vector routing protocol?

A Path Vector routing protocol is characterized by its use of paths as the key mechanism for routing decisions. BGP, or Border Gateway Protocol, employs a path vector mechanism by maintaining the path information that gets updated dynamically as routing information changes. This allows BGP to not only find the best path to a destination but also to keep track of the entire route that data packets will take through the network, which helps to prevent routing loops.

In BGP, the "path" refers to the sequence of Autonomous Systems (AS) that a packet traverses. Each time a BGP router receives route information from a neighboring AS, it adds its AS number to the path attribute. This way, BGP routers can make informed routing decisions based on the entire path taken by the packet, allowing for both policy-based routing and loop prevention.

Other routing protocols mentioned, such as RIP, EIGRP, and OSPF, utilize different mechanisms. RIP (Routing Information Protocol) is a distance-vector protocol that uses hop count as its metric. EIGRP (Enhanced Interior Gateway Routing Protocol) is a hybrid protocol that uses elements of both distance-vector and link-state routing, but does not implement path vectoring. OSPF (Open Shortest Path First)