The reason for asking is to see whether you respect the drivers that drive by.
When you walk using paths A, you're taking the quickest way possible to get from one side to the other. By doing this, you're allowing the cars to wait less and that's a sign of respect.
By walking paths B, you're taking a bit longer to get across. Paths C take a lot longer. When people take these longer paths, they're making the drivers wait longer and that sometimes pisses them off.
Before people say, "Too bad... make them wait!" ... we also go through the same thing when we're driving. If there's no cars around, walking in any path is fine. However, if you see a car coming... stick with paths A for it's the quickest way across.