Which of the following selections most closely defines traces as it is used in the following passage?

He glanced back. The other sled was coming up like an express-train. With half the dogs still over their traces, he cried, "Mush on!" and leaped upon the sled just as the pursuing team dashed abreast of him.

A. noun | two straps that attach something to something else

B. noun | evidence left by someone who is fleeing

C. noun | considerably small quantities of something

D. verb | makes marks over the outline of something else on paper