For these questions you always want to pick the answer that keeps the enzyme concentration constant, increases substrate concentration, and runs the michaelis-menten type of experiment in the presence and absence of the inhibitor. In this case, IN = enzyme, vDNA = substrate, and ODN = inhibitor.
This is based on the m.m. enzyme kinetics model which is plotted on the saturation plot and lwb-plot:
The lwb plot seems to come up more often but if you know how each inhibitor type changes Km and vmax, you can check the lwb plot made from the data run with and without the inhibitor and find out what type of inhibitor ODN might be. In the example graphs above, the competitive inhibitor would show an increase in Km but no changes in vmax. If we saw these graphs after running the trials for ODN, we could say ODN is likely a competitive inhibitor.