How Might Page Migration and Page Replication Actually Reduce System

Multiple Choice

How might page migration and page replication actually reduce system performance?

A) Page replication requires a more complex coherency protocol because the same page can exist at separate nodes.
B) Replicating or migrating a page is more costly than remotely referencing a page a small number of times. If pages that are replicated or migrated are not referenced again at their new nodes, then these strategies slow average memory access time.
C) The information that must be maintained to make good migration and replication decisions can consume substantial memory overhead.
D) all of the above