Why is FastResync enabled automatically for volumes created on thin LUNs?

A.
Volumes based on thin LUNs are more likely to require resync than volumes based on
thick LUNs.

B.
To ensure thin LUNs remain thin should resync be required.

C.
To ensure data written to volumes based on thin LUNs is persistent.

D.
Resync for volumes based on thin LUNs is slower than resync for volumes based on
thick LUNs and FastResync bridges this performance gap.