What are the restrictions for crossing a single broken yellow line?

When it comes to crossing a single broken yellow line, the correct understanding is that it typically indicates that you are allowed to pass another vehicle or change lanes if it is safe to do so. This line serves as a guide that shows drivers that they may cross it, unlike a solid line, which would indicate that crossing is not permitted.

In the context of passing a vehicle, it is essential that drivers must ensure that the road is clear of oncoming traffic, and they must complete the maneuver safely and efficiently. This means being vigilant and recognizing that while it is permitted, it still comes with responsibilities for ensuring it is safe to execute such actions.

The other options provided do not correctly represent the rules associated with a single broken yellow line, as it is not permissible to cross for arbitrary reasons (such as anytime without consideration for safety) or to restrict crossing only for specific times, which do not align with current driving regulations. Therefore, only passing when safe is the correct interpretation of the rules governing this road marking.