Answer: a. the Constitution's failure to precisely define the relationship between American Indian tribes and the national government.
Step-by-step explanation:
The Constitution is a bit vague when it comes to defining the relationship the Federal Government should have with the American Indian Tribes.
This has allowed for the Federal Government to take advantage of loopholes and historically, treat the American Indian tribes unfairly.
Some speculate that the Constitution was deliberately left that way so that such loopholes could be taken advantage of.