Explanation:

- Option 1: Ordinary legislation

- When there's a disagreement between the Lok Sabha and Rajya Sabha over an ordinary bill, a joint sitting can be convened to resolve the deadlock.

- This mechanism allows both houses to debate and vote together.

- Correct Answer

- Option 2: Money Bill

- Money Bills can only be introduced in the Lok Sabha.

- The Rajya Sabha can suggest amendments, but the Lok Sabha is not obligated to accept them.

- No joint sitting is required for Money Bills.

- Option 3: Constitutional Amendment Bill

- These bills require a special majority in both houses separately.

- There is no provision for a joint sitting.

- Option 4: None of the above

- Incorrect, as ordinary legislation does call for a joint sitting.

The answer is option 1, as only ordinary legislation can be settled via a joint sitting if a deadlock occurs.