Yellow lines separate __________.

Yellow lines are used to separate lanes of traffic that are moving in opposite directions. This is an essential detail in road marking that aids in traffic management and safety. By clearly delineating these lanes, yellow lines help prevent head-on collisions, which can be particularly dangerous. When drivers see a yellow line, it indicates that they should not cross it unless it is safe to do so, hence providing a guideline for safe merging and overtaking.

Options that suggest yellow lines separate lanes of traffic moving in the same direction or designate specific lanes for High Occupancy Vehicle (HOV) use are incorrect because those situations typically involve white lines. White lines are designed for separating lanes of traffic traveling in the same direction or indicating special lane designations on roadways.