Hi

well a clear answer

from v$sql there is now way to find out whaether your query used CBO or RBO .Plaese tell your boss that

You should take the sql from the V$sql dump and execute it from the sqlplus prompt..(but since your sql will contain bind variables ) you probably cannot tell whaether you used CBO or RBO

You should enable tracing of the application on the production server
There is simply no other way..

v$sql cannot tell you whaether you used CBO or RBO.tracing of the application on the server is the only way.

regards
Hrishy