Answer
The graph jumps at its discontinuities because of the "per two-ounce" charges.
Work Step by Step
It is seen from the graph that the graph has ‘jumps’ at its discontinuities which are at the points $2,4,6\text{ and 8}$. This is because the graph breaks on the particular intervals of weight and it is not continuous from the starting to the end point. Since the weight of the mail increases per two ounces, the graph has jumps every two ounces.
