Which of the following is the graph of a linear function? a) a coordinate grid is shown with a slanting straight line segment that starts at a point in the second quadrant, cuts the negative x-axis and negative y-axis, and ends at the fourth quadrant. b) a coordinate grid is shown with a u-shaped graph which cuts the axis at 2 points and the negative y-axis at 1 point. c) a coordinate grid is shown with two slanting straight line segments that meet at a point in the first quadrant. d) a coordinate grid is shown with a curved line that cuts the positive axis at 1 point and the y-axis at 2 points.