What type of lane marking separates two-way traffic?

The correct answer is a solid yellow line. In the context of road markings, a solid yellow line indicates that crossing over into the opposing lane of traffic is prohibited, which is essential for safety when dealing with two-way traffic. This marking helps to clearly delineate lanes and maintain order on the road, preventing head-on collisions by signaling to drivers that they must remain in their respective lanes.

In contrast, a dashed yellow line typically allows for passing when safe, which is not suitable for separating opposing traffic in a way that maintains safety. White lane markings are used to separate lanes of traffic moving in the same direction and are not used for two-way traffic delineation. A solid white line serves to indicate that lane changes are discouraged, defining the boundaries for traffic moving in the same direction rather than opposing directions.