Since bank has already communicated to the client abt the charges deduction, so it is assumed that client had deducted those charges of Rs.1000 from cash book on communication date.

Now if the same charges have been eliminated/waived by the bank so the client should add Rs. 1000 to his cash book to get his cashbook tallied with Bank Pass Book

So the answer is (b) Add Rs.1000

PRODUCTION FUNCTION REFERS TO?

Adding Rs. 1000 is correct and the reason is too correctly explained by Manish ji

Mr. Manish is absolutely right.  I am attaching here a link for a video on Bank Reconciliation Statement.  It may be useful to students as well as professionals.  You are requested to give your valuable feedback.

https://www.youtube.com/user/jbsclasses