Only pass into the left lane if there's a _____ yellow line on your lane?

Passing into the left lane where there is a dashed yellow line indicates that it is safe and permissible for drivers to cross over into that lane. A dashed yellow line signifies a zone where overtaking and passing are allowed, hence providing the opportunity to safely maneuver around slower vehicles. This enhances the flow of traffic and ensures that drivers can navigate safely when conditions allow.

In contrast, a solid yellow line indicates that passing is prohibited, as it typically marks a situation where safety is at risk, such as zones with limited visibility or road conditions that make passing dangerous. Double solid yellow lines further reinforce this caution, as they indicate that neither lane can cross the lines to pass. A red line does not pertain to passing regulations and might indicate other restrictions or situations unrelated to lane changes, making the dashed yellow line the only appropriate answer in this context.