A power-driven vessel up to 12 metres long may combine its masthead light and sternlight into a single light. What must this combined light be, and how must it be positioned relative to the sidelights?

1. A red flashing light, positioned below the sidelights
2. An all-round white light, positioned at least 1 metre above the sidelights
3. A green light, positioned level with the sidelights
4. A yellow light, positioned at the stern only