* SET_TABLE_PREFS Procedure
This procedure is used to set the statistics preferences of the specified table in the specified schema.
* Example: Using Pending Statistics
Assume many modifications have been made to the employees table since the last time statistics were gathered. To ensure that the cost-based optimizer is still picking the best plan, statistics should be gathered once again; however, the user is concerned that new statistics will cause the optimizer to choose bad plans when the current ones are acceptable. The user can do the following:
EXEC DBMS_STATS.SET_TABLE_PREFS('hr', 'employees', 'PUBLISH', 'false');
By setting the employees tables publish preference to FALSE, any statistics gather from now on will not be automatically published. The newly gathered statistics will be marked as pending.

During SQL execution, if a cardinality misestimate occurs, then the database creates SQL plan directives. During SQL compilation, the optimizer examines the query corresponding to the directive to determine whether missing extensions or histograms exist (D). The optimizer records any missing extensions. Subsequent DBMS_STATS calls collect statistics for the extensions.
The optimizer uses dynamic sampling whenever it does not have sufficient statistics corresponding to the directive. (B, not C)
E: Currently, the optimizer monitors only column groups. The optimizer does not create an extension on expressions.
Incorrect:
Not A: SQL plan directives are not tied to a specific SQL statement or SQL ID.
Note:
* A SQL plan directive is additional information and instructions that the optimizer can use to generate a more optimal plan. For example, a SQL plan directive can instruct the optimizer to record a missing extension.