An OSPF router (routerA) on the network is running at an abnormally high CPU rate. Using various OSPF debug commands on routerA, the network administrator determines that routerA is receiving many OSPF link state packets from an unknown OSPF neighbor, thus forcing many OSPF path recalculations and affecting routerA’s CPU usage. Which OSPF configuration should the administrator enable to prevent this kind of attack on routerA?

A.
OSPF stub area

B.
OSPF link state advertisement (LSA) filtering

C.
OSPF MD5 authentication

D.
multi-area OSPF

E.
OSPF not-so-stubby area