On a coordinate plane, a piecewise function has 4 lines. The first line has an open circle at (0, 0) and continues horizontally to a closed circle at (1, 0). The second line has an open circle at (1, 4) and continues horizontally to a closed circle at (3, 4). The third line has an open circle at (3, 6) and continues horizontally to a closed circle at (4, 6). The fourth line has an open circle at (4, 10) and continues horizontally with an arrow instead of an endpoint. The cost of parking in a garage, in dollars, can be modeled by a step function whose graph is shown. How much does it cost to park for 3 hours and 45 minutes?

$3
$4
$6
$10