OSPF will be used as the IGP within a campus network. Which things should you consider before deployment?

A.	All areas need to connect back to area 0.
B.	The OSPF process number on each router should match.
C.	NSSA areas should be used when an area cannot connect directly to area 0.
D.	Stub areas should be connected together using virtual links.
E.	ECMP may cause undesired results depending on the environment.