SQL> explain plan for
  2  UPDATE SYSPRD9.PS_PROJ_RESOURCE
  3  SET BI_DISTRIB_STATUS = 'P'
  4  WHERE (BUSINESS_UNIT, PROJECT_ID, ACTIVITY_ID, RESOURCE_ID)
  5  IN
  6  (SELECT BUSINESS_UNIT_PC , PROJECT_ID , ACTIVITY_ID , RESOURCE_ID
  7  FROM SYSPRD9.PS_CA_BI_ERR_TA213
  8  WHERE PROCESS_INSTANCE = 1711564
  9  AND CA_ERROR_TYPE IN ('FPC', 'WTH'));

Explained.

SQL> @E:\oracle\product\10.2.0\db_1\RDBMS\ADMIN\utlxpls

Fri Dec 05                                                                                                                                   page    1
                                                           SQL With Disk Reads > 10 Seconds

Plan hash value: 3537856875                                                                                                                           
                                                                                                                                                      
------------------------------------------------------------------------------------------------------                                                
| Id  | Operation                       | Name               | Rows  | Bytes | Cost (%CPU)| Time     |                                                
------------------------------------------------------------------------------------------------------                                                
|   0 | UPDATE STATEMENT                |                    |     1 |   129 |     4  (25)| 00:00:01 |                                                
|   1 |  UPDATE                         | PS_PROJ_RESOURCE   |       |       |            |          |                                                
|*  2 |   TABLE ACCESS BY INDEX ROWID   | PS_PROJ_RESOURCE   |     1 |    69 |     2   (0)| 00:00:01 |                                                
|   3 |    NESTED LOOPS                 |                    |     1 |   129 |     4  (25)| 00:00:01 |                                                
|   4 |     SORT UNIQUE                 |                    |     1 |    60 |     1   (0)| 00:00:01 |                                                

Fri Dec 05                                                                                                                                   page    2
                                                           SQL With Disk Reads > 10 Seconds

|*  5 |      TABLE ACCESS BY INDEX ROWID| PS_CA_BI_ERR_TA213 |     1 |    60 |     1   (0)| 00:00:01 |                                                
|*  6 |       INDEX RANGE SCAN          | PS_CA_BI_ERR_TA213 |     1 |       |     1   (0)| 00:00:01 |                                                
|*  7 |     INDEX RANGE SCAN            | PSCPROJ_RESOURCE   |  7578K|       |     2   (0)| 00:00:01 |                                                
------------------------------------------------------------------------------------------------------                                                
                                                                                                                                                      
Predicate Information (identified by operation id):                                                                                                   
---------------------------------------------------                                                                                                   
                                                                                                                                                      
   2 - filter("PROJECT_ID"="PROJECT_ID" AND "ACTIVITY_ID"="ACTIVITY_ID" AND                                                                           
              "RESOURCE_ID"="RESOURCE_ID")                                                                                                            

Fri Dec 05                                                                                                                                   page    3
                                                           SQL With Disk Reads > 10 Seconds

   5 - filter("CA_ERROR_TYPE"='FPC' OR "CA_ERROR_TYPE"='WTH')                                                                                         
   6 - access("PROCESS_INSTANCE"=1711564)                                                                                                             
   7 - access("BUSINESS_UNIT"="BUSINESS_UNIT_PC")                                                                                                     

23 rows selected.

SQL> spool off