What statement$($s$)$ would be true for Azure storage system?$$ Your answer: $($A$)$ The partition layer uses the append$-$only data model; $($B$)$The stream layer provides inter$-$stamp replications to ensure high availability; $($C$)$ The$$append operation is atomic; $($D$)$ The partition server keeps two sets of data structures, one$$set for in$-$memory, one set in hard disk stored streams.