Explanation:

- The proposed oil refinery at Pachpadra, Barmer is indeed a joint venture involving Hindustan Petroleum Corporation Limited (HPCL) and the Government of Rajasthan. This collaboration is aimed at boosting local economy and refining capacity.

- Option 1: ONGCL (Oil and Natural Gas Corporation Limited) and Government of India - This option is incorrect as ONGCL is not involved in this specific refinery project.

- Option 2: OIL (Oil India Limited) and Government of Rajasthan - This option is not applicable to the Pachpadra project.

- Option 3: HPCL and Government of India - While HPCL is involved, the direct partner for this refinery is the Government of Rajasthan, not the Government of India.

- Option 4: HPCL and Government of Rajasthan - This is the correct partnership, with HPCL leading the venture and the Rajasthan government as a stakeholder.