External tables using the ORACLE_DATAPUMP access driver have specific characteristics:

C. Creating an external table using the ORACLE_DATAPUMP access driver allows you to select data from other tables, including another external table or a regular table whose rows are stored in database blocks.

A, B, D, and E are incorrect. Specifically:

A is incorrect because creating an external table does not automatically create a directory object; the directory object must exist prior to or be created separately.

B is incorrect as it limits the creation to tables stored in database blocks, which is not a restriction.

D is incorrect because creating an external table does not create a dump file; it reads from an existing dump file created by Data Pump.

E is also incorrect because the dump file is not created as part of the external table creation process.

References:

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "CREATE TABLE" for External Tables