The index of leading indicators is used to predict changes in business cycles. The correct option among all the options that are given in the question is the first option or option "a". It is basically used to predict the future of the upcoming economy. It can also be said that it does not always yield the perfect result.
C. Federalism
What is funny, is I'm am learning about this in school too!
They had to walk the north west river it the longest river