Which of the following is$/$are correct for Google's Bigtable solution?

Question $6$Select one or more:

a$.$

In a $($big$)$table$,$ each value is uniquely determined by a row key, column key, and a timestamp.

b$.$

Google's Bigtable supports transactions across row keys.

c$.$

Google's Bigtable uses the shared$-$nothing architecture in which the nodes share memory but do not share disk.

d$.$

Google's Bigtable dynamically partitions a $($big$)$ table into tablets based on column keys.

e$.$

Google's Bigtable uses supercomputers to scale out.