问题：

[单选] 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