Amendment 10 sets up a system of reserved powers which gives all powers not granted to the central government to the states for example, marriage laws, building roads, collecting taxes, etc.
The U.S. Constitution refers to the Constitution of the whole country, not the individual states, so the second option can't be the right one. Also, the power is limited and there is a way to have amendments, so the right answer is this one:
<span>It explains the organization of the federal government</span>
Stupid question. Europeans have different cultures