Explanation:

Article 164 clearly states that the Council of Ministers is collectively responsible to the legislative assembly. This means that all the ministers own joint responsibility to the legislative assembly for all their acts of omission and commission. When the legislative assembly passes a no-confidence motion against the Council of Ministers, all the ministers have to resign including those ministers who are from the legislative council. Each minister need not resign separately; the resignation of the Chief Minister amounts to the resignation of the entire Council of Ministers. Hence option 2nd is correct.