The answer is option d: stop lines. Solid white lines are used to separate different lanes and discourage lane changes near intersections and other areas where lane changes might be dangerous. However, stop lines are not marked by white lines. Stop lines indicate the place where drivers should stop before entering or crossing a roadway. They are typically marked by a solid white line and a sign that reads "STOP" or contains a "STOP" symbol. Other types of lines that are not marked by white lines include the double yellow lines, which are used to separate traffic flowing in opposite directions, and the single yellow line, which is used to mark the outer limits of a lane for passing.