Some advice to all prospective applicants. You have obviously by this point worked out how to get the application documents. At the bottom of the documents you will see another link that is called "Instruction Guide". It's pretty clear.
In answer to your question, had you read it, you would have seen: -
Question 4
Immigration Office requested for the processing of your application
Indicate the name of the Immigration Office which serves:
your country of nationality, or
the country in which you are residing, provided that you have been lawfully admitted to that country for at least one (1) year.
Note: Do not select the Centralized Intake Office (CIO) as the immigration office requested to process your application. Although you may be required to submit your application to the CIO, you must indicate the name of an appropriate visa office using the criteria above.
Note:If you are applying for refugee protection from within Canada or being sponsored from within Canada, this question does not apply to you. Go to Question 5.
It also provides a link that shows in detail the names of the offices and which ones should be selected...
In answer to your question, had you read it, you would have seen: -
Question 4
Immigration Office requested for the processing of your application
Indicate the name of the Immigration Office which serves:
your country of nationality, or
the country in which you are residing, provided that you have been lawfully admitted to that country for at least one (1) year.
Note: Do not select the Centralized Intake Office (CIO) as the immigration office requested to process your application. Although you may be required to submit your application to the CIO, you must indicate the name of an appropriate visa office using the criteria above.
Note:If you are applying for refugee protection from within Canada or being sponsored from within Canada, this question does not apply to you. Go to Question 5.
It also provides a link that shows in detail the names of the offices and which ones should be selected...