Explanation:

- Immovable property refers to real estate or property that cannot be moved. It typically includes land and any structures on it.

- Document registration is often necessary to legally validate ownership or property transactions. For situations involving immovable property, the need for documentation can vary based on the property's value.

- Option 1: Less than Rs. 1000 - Often seen as a low threshold, but documentation might still be required for official purposes.

- Option 2: Less than Rs. 10000 - Considered a moderate amount, legal requirements could vary.

- Option 3: Less than Rs. 100 - This is the correct option. Traditionally, properties valued under Rs. 100 do not require registration documentation.

- Option 4: Less than Rs. 100000 - Generally too high a threshold, and documentation is almost always required.

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