You are implementing OSPF as the IGP using a single OSPF area design. The router memory usage for OSPF is too high. Which two methods can lower the OSPF memory usage?

A.	Enable OSPF synchronization
B.	Implement multi-area OSPF
C.	Enable OSPF sham links to reduce the number of LSAs
D.	Implement route summarization on the ABRs
E.	Enable route leaking between Level 1 and Level 2 areas