Given the task definition and input, reply with output. This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: Because the states were preexisting political entities, the U.S. Constitution did not need to define or explain federalism in any one section but it often mentions the rights and responsibilities of state governments and state officials in relation to the federal government. The federal government has certain express powers (also called enumerated powers) which are powers spelled out in the Constitution, including the right to levy taxes, declare war, and regulate interstate and foreign commerce. In addition, the Necessary and Proper Clause gives the federal government the implied power to pass any law "necessary and proper" for the execution of its express powers. Other powersthe reserved powersare reserved to the people or the states. The power delegated to the federal government was significantly expanded by the Supreme Court decision in McCulloch v. Maryland (1819), amendments to the Constitution following the Civil War, and by some later amendmentsas well as the overall claim of the Civil War, that the states were legally subject to the final dictates of the federal government.
Why did the constitution have to explain federalism?