The options are:
Always import database optimizer statistics regardless of whether they are questionable.
Do not import or recalculate the database optimizer statistics.
Import database optimizer statistics only if they are not questionable. If they are questionable, then recalculate the optimizer statistics.
Do not import the database optimizer statistics. Instead, recalculate them on import. This requires that the original export operation that created the dump file must have generated the necessary
ANALYZE statements (that is, the export was not performed with
ANALYZE statements are included in the dump file and used by the import operation for recalculation of the table's statistics.