What is EMC best practice for creating more than one snapshot per directory?

What is EMC best practice for creating more than one snapshot per directory?
A . Create snapshots with shorter expiration periods assigned to snapshots that are generated more frequently; use longer expiration periods assigned to snapshots that are generated less frequently
B . Create snapshots with longer expiration periods assigned to snapshots that are generated more frequently; use shorter expiration periods assigned to snapshots that are generated less frequently
C . Only create snapshots with shorter expiration periods assigned to snapshots that are generated more frequently
D . Only create snapshots with longer expiration periods assigned to snapshots that are generated less frequently

Answer: A