[CSAT App Q] Your hands are not tied with optional subject choice in prelim form

[CSAT App Q] Your hands are not tied with optional subject choice in prelim form

I have a doubt regarding the application form, though I have send the offline application form through post, I have one query which is eating my mind from past few days, I have mentioned in the FORM-E (offline application form) my mains optional and centre of the exam, because of some conditions I had to change one of the optional , though I should have thought this before filling the form, but I could not do so. Suppose I qualify the prelims can I put changed optional in the DETAILED APPLICATION FORM of the mains, or I will be bound to use the same optional I have marked in form-e, kindly help me in this regards, I have called UPSC facilitation counter many times during weekdays they are not lifting, and even those of my friends who have qualified the exam are unable to answer my query.

Ans:
Don't worry, the notification says

"This column, i.e. 21(III) [Mains subject choice] is optional and is only for statistical purposes.
Candidates who qualify the Civil Services (Preliminary) examination 2011 will be required to provide this information at the time of filling up of the Detailed Application Form (DAF) for the Civil Services (Main) Examination 2011]. "