Which of the following is a limitation on state powers?

The limitation on state powers indicated in the response is that states are prohibited from coining money. This limitation is rooted in the U.S. Constitution, specifically Article I, Section 10, which explicitly restricts states from engaging in activities that could undermine the federal government's authority and the uniformity of the national currency. The framers of the Constitution recognized the necessity for a stable and cohesive monetary system, which is crucial for national unity and economic stability.

Allowing individual states to coin their money could lead to a fragmented economic landscape, with varying currencies that could confuse commerce and trade. By centralizing the power to mint currency, the federal government ensures that there is a consistent medium of exchange throughout the country, thus upholding the economic integrity of the nation.

In contrast, the other options represent powers or privileges that are either granted to the federal government or are not unrestricted for states. For example, states are not allowed to enter into treaties with foreign countries, control immigration policies fully, or tax imports and exports without restrictions. These limitations ensure that certain powers remain cohesive under federal control to maintain national integrity and diplomacy.