If one were to prepare a graph with the vertical axis representing total expense and the horizontal axis representing units of production, how would a line representing a mixed cost appear?

As a straight line which connects with the origin and slopes upward to the right.

As a horizontal line which connects with the vertical axis at a point above the origin.

As a sloping line which connects with the vertical axis at a point above the origin.

As a curve from the origin and convex to the horizontal axis.