33. What light signal shall be exhibited for a vessel engaged on pilotage duty while underway? (A) At or near the masthead, two all-round lights in a vertical line, the upper being red and the lower white. Sidelights and a sternlight. (B) At or near the masthead, two all-round lights in a vertical line, the upper being white and the lower red. Sidelights and a sternlight. (C) At or near the masthead, two all-round lights in a vertical line, the upper being green and the lower red. Sidelights and a sternlight. (D) At or near the masthead, two all-round lights in a vertical line, the upper being red and the lower green. Sidelights and a sternlight.