Which of the following is NOT a requirement for the filing of a divisional application?

To understand why narrowing the claims is not a requirement for filing a divisional application, it's important to first clarify what a divisional application is. A divisional application is filed when an applicant has multiple inventions in a single patent application, and it is used to split these inventions into separate applications. This often arises from a situation where the original application is found to have more than one distinct invention, which can be problematic since the United States Patent and Trademark Office (USPTO) typically requires that a patent application only claims a single invention.

The process of filing a divisional application allows the applicant to seek protection for distinct inventions without having to argue or narrow down the claims of the original application. Hence, while the first requirement reflects the necessity of distinct inventions and the second deals with the continuation of the original application, there is no requirement to narrow down the claims for the divisional application itself.

Furthermore, the payment of the appropriate fee is a standard requirement for any patent application, including divisional applications. Therefore, claim narrowing is not a necessary condition for the issuance of a divisional application, affirming the correctness of that answer.