From a design perspective which two of the following OHPF Statements are most relevant？（）

A. OSPF stub areas can be thought of as a simple form of summarization
B. OSPF cannot filter intra area routes
C. An ARR ran only exist in two areas - the backbone and one adjacent area
D. Performance issues in the Backbone area can be offset by allowing some traffic to transit anon-backbone area
E. the size of an area （the LSDB） will be constrained by the size of the IP MTU