What does a white line separating lanes allow?

A white line separating lanes indicates that lane changes are permitted. This is a common practice on roadways, where the white line serves to demarcate different lanes of traffic traveling in the same direction. Drivers are generally allowed to cross the white line to change lanes, provided it is safe to do so and does not violate any traffic rules or cause a hazard to other vehicles.

In contrast, a yellow line usually indicates lanes going in opposite directions, and crossing these lines often signifies prohibited actions. Other options like special lane usage for buses or designated lanes for bicycles generally involve different colored lines or specific signage that clearly indicate such regulations. Therefore, the correct answer reflects the standard interpretation of a white line's purpose in traffic management.