This is the correct answer but it is worth pointing out copyright being spelled out specifically in the first amendment recognizes that this is something that he government would normally not have authority to enact because it goes against more fundamental rights. The first amendment also restricts the authority of the government when it comes to copyright by requiring it to be done "To promote the Progress of Science and useful Arts" and for the aritificial monoboly to be "for limited Times". It isn't clear that the current implementation of copyright still falls within either of these limitations.