The graph represents the cost of catering a dinner as a function of the number of guests. On a coordinate plane, a graph titled Dinner Catering Cost shows Guests Served on the x-axis and Total cost in dollars on the y-axis. A piecewise function has 3 lines. The first line has an open circle at (0, 100) and goes up to a closed circle at (40, 600). The second line has an open circle at (40, 700) and goes up to a closed circle at (80, 1300). The third line has an open circle at (80, 1600) and goes up to (100, 2000).
What is the catering cost for a dinner with 40 guests?

$400
$600
$700
$800