What indicates the outside edge of the traffic lane, and may be crossed only by traffic moving to or from the shoulder?

The correct answer is the solid white line. This type of line indicates the boundary of a traffic lane and is used to mark the edges of lanes in the same direction of travel. It serves as a guideline for drivers, helping them stay within their lane while informing them that crossing the line is discouraged, unless necessary for safely entering or exiting the roadway, such as moving onto the shoulder or making a turn.

Choosing the solid white line in this context is important because it conveys the message that while lane changes are generally not recommended, there are specific circumstances (like accessing the shoulder) where crossing is permitted. This allows for safe navigation around obstacles or stopping in emergency situations while maintaining overall traffic flow and safety.

In contrast, other line types serve different purposes: the dashed white line indicates that lane changes are allowed; the solid yellow line signifies no passing in either direction; and the broken yellow line allows passing only if it is safe to do so. Understanding these distinctions is crucial for safe driving and adherence to traffic regulations.