Which of the following could be considered a leading indicator to predict changes in the real gdp?

It's actually (Economist Calculations Which Accurately Predict Business Cycles)

B.The power to ratify changes to the Constitution

Explanation:

The Founding Fathers designed the US Constitution to be hard to amend. They did so because they wanted to preserve the political deals that made the US Constitution possible.

Article 5 of the US Constitution says that an amendment can be proposed either by 2/3 majority in the House and the Senate or by a convention called into being by Congress.

After that, the amendment has to be ratified by 3/4 of the states, this means that the federal government does not have the power to ratify any amendment, the states have to.