Ok what should be in the letter should it be dated and signed. Thanks.
In the letter, you should explain to CIC that the question was a bit confusing so you want to further explain your situation. Tell them that yes, you did infact live outside of the country during your eligibility period as you have indicated on the citizenship application form but that you are not a Crown Servant Family Member or a Crown Servant Applicant, so none of the questions in the form CIT-0177 are applicable to you. Also, include in the letter your eligibility period, the period of time your lived outside the country during your eligibility period and when you received Canadian Permanent Residence.
Yes, you also need to date and sign the letter, also include the address of where the Citizenship Application is being sent and reference the letter "RE: Question 9c - Application for Canadian Citizenship Adults CIT-0002. I would suggest, date be same date that is on your application. But please don't use what I wrote here word for word. Use your own wording. Good luck!