In $2014,$

Amazon.com 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?

Amazon's revenue when the price is $$79$ is