To generate recommendations to improve the performance of a set of SQL queries in an application， you execute the following blocks of code：   BEGIN  dbms_advisor.create_task（dbms_advisor.sqlaccess_advisor，’TASK1’）；  END； /  BEGIN  dbms_advisor.set_task_parameter（’TASK1’，’ANALYSIS_SCOPE’，’ALL’）； dbms_advisor.set_task_parameter（’TASK1’，’MODE’，’COMPREHENSIVE’）；  END；  /  BEGIN  dbms_advisor.execute_task（’TASK1’）；  dbms_output.put_line（dbms_advisor.get_task_script（’TASK1’））；  END；  /  The blocks of code execute successfully；however，you do not get the required outcome.  What could be the reason？（）  

A.  A template needs to be associated with the task.

B.  A workload needs to be associated with the task.

C.  The partial or complete workload scope needs to be associated with the task.

D.  The type of structures （indexes， materialized views， or partitions） to be recommended need to be  specified for the task.