The purpose of double-broken yellow lines is to:

Double-broken yellow lines serve the purpose of separating traffic lanes that are moving in opposite directions. This means that vehicles traveling in each direction are given their own designated lane, promoting safety and clarity on the road. Drivers should be aware that while they can cross these lines to pass another vehicle, they must exercise caution and ensure it is safe to do so, as these lines indicate that opposing traffic is present. Understanding the significance of these lines helps drivers navigate safely and reduces the potential for accidents between oncoming vehicles.

The other choices do not correctly describe the function of double-broken yellow lines. No passing zones are typically indicated by solid lines, and designated bus lanes and lane changes in busy areas are different traffic management strategies altogether.