There is no direct statistics showing the usage of temp tablespace in the Alternatives grid. However, one may be interested in the "Sorts (Disk)" statistic which show the number of sort operations that require disk (which implies the use of temp tablespace).
Another statistic one can check is on the actual execution plan (note that this is not listed in the Alternatives grid but on the plan only). It is the TEMP_SPACE column in a plan. Check the Actual Plan after test run. This TEMP_SPACE column shows the temporary space used in bytes by the plan operation.
If one does not see the TEMP_SPACE information in your plan, right-click the plan to select "Plan Options..." and make sure the column is selected to be visible. Another possibility is to write to the DBMS_XPLAN format if you are using the latest version 9.0.