Debentures which are transferable by mere delivery are:

Bearer debentures

The correct answer is option 3- Bearer debentures.

Debentures which are transferable by mere delivery are Bearer debentures.

Bearer debentures are not registered in the name of the holder and are payable to the bearer of the instrument. They are transferable by mere delivery, meaning ownership can be transferred simply by physically handing over the debenture certificate to another party, without the need for any formal registration or endorsement.

OTHER OPTIONS

• Registered Debentures: Registered debentures have detailed information about debenture holders, including their names, addresses, and holdings, recorded in a company-maintained register. These debentures can only be transferred through a formal transfer deed.

• Unsecured Debentures: Unsecured debentures do not have a specific claim on the company's assets. However, in the event of default, a floating charge may be created on these debentures. Generally, companies do not issue these types of debentures.