Final answer:
The center lane marked by single broken yellow lines on both sides is usually for passing or changing lanes, making option 1 correct. It's essential to look for specific signs or different lane markings for correct use, as some center lanes could be designated for turns or other purposes.
Step-by-step explanation:
If the center lane is marked by a single broken yellow line on both sides, typically, this indicates that the center lane is open for passing or changing lanes. It means that vehicles traveling in either direction may use the lane for passing slower traffic when it is safe to do so, as long as there is no opposing traffic using the lane. It's important to merge back into the correct lane as soon as you've safely and successfully passed the vehicle.
Moreover, some roadways may have designated center lanes for left turns or other purposes, marked with different signs or road markings. In the case of a center turn lane, it would usually be indicated by specific signage and possibly by solid and broken line combinations. Always look for road signs and follow local traffic laws to understand the proper use of the center lane.