In the USA, each branch of government has powers that have been defined as theirs by the Constitution. However, there is a notion of other powers that are not explicitly mentioned in it. In the case of Congress, such implied powers are deemed to be “necessary and proper”, that is to say, that it is understood that although they are not granted explicitly by the Constitution, they are logically and reasonably required to exercise those powers which are explicitly granted by the Constitution. Since the powers of coining money, acquiring territory and declaring war are explicitly granted by the Constitution to the federal government, the correct answer for this question would be building highway systems, which is an implied power (that also happens to be a concurrent power (a power that is exercised both by the federal and the state governments).
