Native Americans have been hunterers and gatherers up to the period when growing crops became available to them/when they discovered growing crops is a thing that could be done. The reason for this is that when you've started growing crops, you can safely stay on one spot and have a sufficient supply of food for a longer time period - this wasn't available before. However, even with the coming of agriculture, the still hunted and gathered as it was an important aspect of their life.
Answer:
D. The federal government can only function effectively if it has the ability to collect taxes.
D. It did not allow for a centralized government