Ok. I got it.
Code:
Now look at the tkprof output:
call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        4      0.01       0.01          0          0          0           0
Execute      4      0.00       0.00          0          0          0           0
Fetch        4      5.44       5.31          0    2585652          0           4
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total       12      5.45       5.33          0    2585652          0           4
The SQL was parsed 4 times and executed 4 times. The CPU time was 5.33. So the average CPU time was 1.33 seconds and it did 2.5 Miilion LIOs.

Second, there is a huge difference between autotrace explain plan and tkprof output row source. Why? Either statistics are missing on tables and indexes or some init parameters are not set correctly. What's the value for optimizer_mode you set?

As I said earlier, the least number of rows was returned by CB_STANDARD table. Make this as driving table.
Use LEADING hint. Post the autotrace plan and tkprof output. Attach the entire trace file.

Tamil