When an OSPF design is planned, which implementation can help a router not have memory resource issues?（）

A、Have a backbone area (area 0) with 40 routers and use default routes to reach external destinations

B、Have a backbo ne area (area 0) with 4 routers and 30,000 external routes injected into OSPF

C、Have less OSPF areas to reduce the need for interarea route summarizations

D、Have multiple OSPF processes on each OSPF router. Example, router ospf 1, router ospf 2