Which three statements are true about logical structures of the Oracle database? (Choose three.)
A.
Each segment contains one or more extents.
B.
Multiple tablespaces can share a single data file.
C.
A data block is the smallest unit of input/output (I/O) in data files.
D.
It is possible to have tablespaces of different block sizes in a database.
E.
Each data block in the database always corresponds to one operating system block.
Why not B?
One tablespace may have many datafiles but one datafile can only be part of one and only on tablespace.