'Interest paid on debentures to debenture holders' is what type of activity for a financial enterprise in the cash flow statement?

Operating activity

Operating activities are the activities that constitute the primary or main activities of an enterprise. For example, for a company manufacturing garments, operating activities are procurement of raw material, incurrence of manufacturing expenses, sale of garments, etc. These are the principal revenue generating activities (or the main activities) of the enterprise and these activities are not investing or financing activities. The amount of cash from operations’ indicates the internal solvency level of the company, and is regarded as the key indicator of the extent to which the operations of the enterprise have generated sufficient cash flows to maintain the operating capability of the enterprise, paying dividends, making of new investments and repaying of loans without recourse to external source of financing. Cash flows from operating activities are primarily derived from the main activities of the enterprise. They generally result from the transactions and other events that enter into the determination of net profit or loss. Examples of cash flows from operating activities are:

Cash Inflows from operating activities-  cash receipts from sale of goods and the rendering of services.  cash receipts from royalties, fees, commissions and other revenues.
Cash Outflows from operating activities  Cash payments to suppliers for goods and services.  Cash payments to and on behalf of the employees.  Cash payments to an insurance enterprise for premiums and claims, annuities, and other policy benefits.  Cash payments of income taxes unless they can be specifically identified with financing and investing activities.
The net position is shown in case of operating cash flows. An enterprise may hold securities and loans for dealing or for trading purposes. In either case they represent Inventory specifically held for resale. Therefore, cash flows arising from the purchase and sale of dealing or trading securities are classified as operating activities. Similarly, cash advances and loans made by financial enterprises are usually classified as operating activities since they relate to main activity of that enterprise.