INLAND ONLY While underway you sight the lights shown in illustration D081RR below with the yellow lights flashing, what action should you take?

Correct Answer: Option C — pass between the two sets of vertical red lights

33 CFR 83.27(b) mandates that the two red lights indicate the side of the obstruction, while the two green lights indicate the side on which a vessel may safely pass. Therefore, you must navigate between the two sets of vertical red lights to avoid the obstruction.