An online tablespace，TEST_TBS，is full and you realize that no server-managed tablespace threshold alerts were generated for the TEST_TBS tablespace.  What could be the reason，if the TEST_TBS tablespace does not include autoextensible data files？（）  

• A、 TEST_TBS is a small file tablespace.
• B、 TEST_TBS is a bigfile tablespace （BFT）.
• C、 TEST_TBS is the default temporary tablespace.
• D、 TEST_TBS is a dictionary-managed tablespace.