Which of the following correctly pairs each type of debenture with its defining characteristic?

Debentures are classified along three dimensions. Security: Secured debentures are backed by a specific charge (fixed or floating) on company assets  if the company defaults, debenture holders can claim those assets; Unsecured debentures (also called naked debentures) carry no charge and are backed only by the company’s general creditworthiness  carrying higher risk, hence typically higher interest rates. Convertibility: Convertible debentures can be converted into equity shares at a pre-specified conversion ratio and time (e.g., after 18 months at a ratio of 1 debenture = 10 equity shares); Non-convertible debentures (NCDs) remain as debt instruments until maturity. Redemption: Redeemable debentures have a fixed maturity date on which the principal is repaid; Irredeemable debentures (perpetual debentures) have no fixed maturity and are not repaid during the company’s normal lifetime  they pay interest perpetually. In practice, NCDs are the most commonly issued form in India’s corporate bond market.