b. RIP is a distance vector protocol whereas OSPF is a link state protocol.
Far and away the greatest functional difference between these IP
routing protocols is the mechanism by which they operate - i. e.
distance vector vs. link state. OSPF allows for information about
specific links to be exchanged between routers - with RIP, the only
available information is the entire routing table, with only networks
and metrics being advertised periodically.
Reference: Comer, Internetworking with TCP/IP, Chapter 15