When LUN mirroring is used, when is data written to the mirror?

A.
Data is written to the active LUN and replicated to the mirrored LUN during garbage
collection.

B.
Data is written to the active LUN first, then replicated to the mirrored LUN.

C.
Data is written to both LUNs simultaneously.

D.
Data is written to the active LUN and replicated to the mirrored LUN at specified time
intervals.