Explanation:

- A Muslim gift (Hiba) is a transfer of property made voluntarily and without consideration by a Muslim to another person.

- ?? It is not compulsory to register a Muslim gift, even if it relates to immovable property, as long as the transfer is made by delivery of possession.

- Option 1 (Compulsorily registrable): Incorrect. Muslim gifts are not required by law to be registered.

- Option 2 (Not compulsorily registrable): Correct. Registration is not mandatory.

- Option 3 (Optionally registrable): Gift can be optionally registered, but not mandatory.

- Option 4 (Not necessary to register): Similar to option 2, but the terminology of option 2 is more apt.

Correct Answer:

Option 2: Not compulsorily registrable