Which of the following is the graph of a linear function?
1. a coordinate grid is shown with a slanting straight line segment that starts at a point in the first quadrant, cuts the x-axis and y-axis and ends at the third quadrant.
2. a coordinate grid is shown with an inverted u-shaped graph that cuts the axis at 2 points and the positive y-axis at 1 point.
3. a coordinate grid is shown with two slanting straight line segments that meet at a point on positive y-axis.
4. a coordinate grid is shown with two slanting straight line segments that meet at a point in the second quadrant.