In the Indian Constitution, legislative powers are divided between the Union (central) government and the State governments. The Union List, State List, and Concurrent List mention all the legislative subjects and cover the entire legislative business. However, if there is an item that is not mentioned in any of these lists, then the Parliament has the power to legislate on that item. This means that option-1 "Parliament only" is the correct answer. The Parliament has the authority to legislate on any subject that is not specifically mentioned in the Union List, State List, or Concurrent List. Therefore, if there is a legislative matter that is not covered by any of these lists, it falls under the jurisdiction of the Parliament.