How can the payment for debentures be structured?

The correct answer is option 3- In installments on application, on allotment, and on various calls.

Debenture issuers have flexibility in structuring the payment for debentures. The payment structure can vary, but a common method is to require investors to make payments in installments. Investors are required to make payments in installments at different stages of the debenture issuance process. It allows for more flexibility for both the issuer and investors, as payments are spread out over time.