The singular noun in this sentence would be the word "Sand" because it's talking about the "Hot sand".
He walked across the hot "sand", hot is used to describe the word sand.
Thus your answer.... B. sand.
Hope this helps. :)
The NCAA believes in giving coaches credit for the success but not the players. I believe that the players should be paid more than scholarships and small payments, because there would be not sport or game without the players.
Could you post the passage?