In​ 2014, Amazon considered raising the annual price of its Amazon Prime shipping and​ streaming-video service from​ $79 to​ $99 per​ year, a​ 25% increase. Such a price increase would be the first in this​ program's nine-year history. Let the figure to the right show the demand for Amazon memberships per year in millions. Using the letters in the graph (A, B, and C and a or sign where appropriate), what area represents Amazon's original revenue, before any price increase?