25、Which is true about logical and physical database structures? (Choose the best answer)

A. An undo tablespace has a temp file instead of a data file.

B. A segment can consist of extents of different sizes.

C. A permanent tablespace can only contain tables segments and index segments.

D. A tablespace can consist of data blocks of different sizes.

E. An extent always consists of physically contiguous data blocks in storage.

Correct Answer: B