Which two options are valid checks that should be performed first to verify proper OSPF operation?

You are troubleshooting an OSPF problem where external routes are not showing up in the
OSPF database. Which two options are valid checks that should be performed first to verify
proper OSPF operation? (Choose two.) Select 2 response(s).

A.
Are the ASBRs trying to redistribute the external routes into a totally stubby area?

B.
Are the ABRs configured with stubby areas?

C.
Is the subnets keyword being used with the redistribution command?

D.
Is backbone area (area 0) contiguous?

E.
Is the CPU utilization of the routers high?