The options are not shown, since this is one of the 1,000 paid questions.
Buy all 1,000 questions now
“Lane […] The lateral space required for the passage of a four-wheel vehicle. Lanes are often marked out with lines, but they do not have to be.” (Du och jag i trafiken [You and me in traffic], 28th Edition, page 114)
It is clear that two cars can fit side by side in each direction. The road thus has 4 lanes.
More examples of explanations: