Answer:
D.
Step-by-step explanation:
Option A. There are more democrats than republicans in Congress contains facts that can be confirmed and it not arguable
Option B. The United States has 50 states contains facts that can be confirmed and it not arguable
Option C. The constitution divides powers between the federal government and state government contains facts that can be confirmed and it not arguable
Option D. Senators should not have term limits is a claim that is arguable because it has been stated in the law that a senator can't use more than two tenure. For them to have more than two tenure, there has to be a debate.