Which consequence of columbus's voyages had the largest impact on american indians?

The correct answer to this open question is the following.

The consequence of Columbus's voyages that had the largest impact on American Indians was the many diseases that the Spaniards conquerors brought to the Americas. These diseases killed thousands of Native Americans. Historians believed that 1/3 of the total Native American population disappeared due to the many new diseases brought by the European conquerors. We are talking about diseases such as chickenpox, smallpox, malaria, and influenza. The Native American Indians were clean and healthy people. The Europeans were totally different.

trade regulation is a field of law, often bracketed with antitrust (as in the phrase “antitrust and trade regulation law”), including government regulation of unfair methods of competition and unfair or deceptive business acts or practices. antitrust law is often considered a subset of trade regulation law. franchise and distribution law, consumer protection law, and advertising law are sometimes considered parts of trade regulation law.

in general the theory of economics says that the more open to trade a country is the better   the result for the same country and the whole economies.

in real life countries impose taxes, quotas, etc which is not so good for the economies.

this kind of commercial war between the usa and china is slowing down the growth of the whole world so we can say that it is a draw back of trade regulations. and the free trade agreements are benefits of trade regulations.