Which two statements are true regarding a tablespace? (Choose two.)

A tablespace is a logical structure scoped to a single Oracle database instance and cannot span or be shared across multiple databases.

A tablespace can have one or more data files added to it via ALTER TABLESPACE ADD DATAFILE, allowing it to grow beyond the size limits of a single file.

While a tablespace can reference blocks from multiple data files, blocks within a tablespace are all the same size (DB_BLOCK_SIZE) - the phrasing implies variable block sizes across files, which Oracle does not support at the tablespace level.

A tablespace can contain segments of different sizes - for example, a small lookup table segment and a large fact table segment can coexist in the same tablespace, each occupying a different amount of space.

A nonpartitioned segment must reside entirely within a single tablespace; a tablespace cannot contain only a partial nonpartitioned segment, because the entire segment is assigned to one tablespace.