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