How does Douglass put an end to Covey's brutal treatment of him? 
 a. He gets a root to carry in his right pocket to keep Covey from striking him.
 b. He hides in a cornfield when Covey is seeking him to whip him.
 c. He attacks Covey and beats him severely enough that Covey fears for his reputation as a slave-breaker.
 d. He tries to work so well that Covey will have no reason to whip him.