What is the difference between a mirror and a backup replication policy?

What is the difference between a mirror and a backup replication policy?
A . Mirror replication policies can retain more Snapshot copies at the destination than at the source.
B . Backup replication policies are faster than mirror replication policies.
C . Backup replication policies can retain more Snapshot copies at the destination than at the source.
D . Mirror replication policies are faster than backup replication policies.

Answer: C