We Are Investigating the Relationship Among Three Variables

We are investigating the relationship among three variables. We have graphed two of them. Suppose that the variable that is not measured on the x-axis or the y-axis changes. Then, there is

A) an omitted variable.
B) a violation of the absence of trend assumption.
C) a movement along the plotted curve.
D) no impact on the plotted curve because the variable is not measured on either of the axes.
E) a shift in the plotted curve.