Answer:
Buck learns quickly because his teachers are strict and unforgiving
Step-by-step explanation:
According to the excerpt from The Call of the Wild by Jack London, Buck was intentionally placed between Dave and Solleks because he was a keen learner who obeyed instructions.
His instructors Dave and Francois were ready to nip him when he strayed so because of this, he kept in line and kept Dave and Solleks in line too
Buck's behavior supports the theme that "one must lead with a firm hand" because his teachers never fail to nip him if the need arises.