Buck had been purposely placed between Dave and Sol-leks so that he might receive instruction. Apt scholar that he was, they were equally apt teachers, never allowing him to linger long in error, and enforcing their teaching with their sharp teeth. Dave was fair and very wise. He never nipped Buck without cause, and he never failed to nip him when he stood in need of it. As Francois's whip backed him up, Buck found it to be cheaper to mend his ways than to retaliate. Once, during a brief halt, when he got tangled in the traces and delayed the start, both Dave and Sol-leks flew at him and administered a sound trouncing. The resulting tangle was even worse, but Buck took good care to keep the traces clear thereafter; and ere the day was done, so well had he mastered his work, his mates about ceased nagging him. Francois's whip snapped less frequently, and Perrault even honored Buck by lifting up his feet and carefully examining them.

How does Buck’s behavior support the theme "one must lead with a firm hand”?
A. Buck learns quickly because Dave never nips without cause.
B. Buck becomes a leader because other dogs respect his authority.**
C. Buck learns quickly because his teachers are strict and unforgiving.
D. Buck excels because he remembers the man with the red sweater.

Buck learns quickly that Dave never nipped Buck without cause

To determine how Buck's behavior supports the theme "one must lead with a firm hand," we can analyze the given excerpt.

In the passage, it is mentioned that Buck had been purposefully placed between Dave and Sol-leks in order to receive instruction. Both Dave and Sol-leks were described as apt teachers and never allowed Buck to linger long in error. They enforced their teaching with their sharp teeth, indicating that they were strict and uncompromising in their approach.

Furthermore, it is mentioned that Dave, who was fair and wise, never nipped Buck without cause, and Buck learned quickly because of this. This suggests that Buck responded positively to the firm discipline and guidance provided by Dave.

Additionally, the passage states that Buck's mates about ceased nagging him as he mastered his work, indicating that they respected his authority as a result of his improvement.

Based on this information, we can conclude that Buck's behavior supports the theme "one must lead with a firm hand" because it demonstrates that he responds positively to strict and uncompromising guidance, which allows him to learn and earn the respect of others.

Therefore, the correct answer is B. Buck becomes a leader because other dogs respect his authority.