What Is One of the Reasons That Power and Responsibility

What is one of the reasons that power and responsibility of the presidency has grown since the early presidency?

A) The United States became a world power.
B) The United States became a simple free market economy.
C) The President's role increased, so the role of government could decrease.
D) The more contemporary presidents had to exercise their powers as commander in chief while earlier presidents did not.
E) The budget for government agencies has decreased leaving more responsibility to the president.