To solve this question, the user needs to have knowledge of the IMPORT command in SQL.

The correct answer is:

D. Both a and b

Explanation:

The IMPORT command is used to import data from an external file into a SQL database. The IMPORT command has several parameters, one of which is the "PARAMETERS" parameter. The "PARAMETERS" parameter has several subcommands, including "INTOEMPTY" and "OBJECTS".

• The "INTOEMPTY" subcommand is used to import data into an empty table.
• The "OBJECTS" subcommand is used to import data into an existing table.

Therefore, option D is correct because both subcommands "INTOEMPTY" and "OBJECTS" are subcommands of the IMPORT parameter.