A lighting products company has put a new brand of solar lightbulbs on the market. The graph shows the estimated revenue, in millions of dollars, as the selling price of the lightbulb varies.

A graph shows the lightbulb revenue at (0, 0) with millions of dollars on the x-axis and ending at (8, 2) height in feet on the y-axis.

What selling price is expected to produce the maximum revenue?