The conflict of Buck VS Spitz is the most important to the development of Buck as a character in "The Call of the Wild". This conflict is essential because it reveals Buck's instinctual nature, his growth in strength and assertiveness, and his transformation into a dominant and powerful sled dog. The rivalry and eventual fight between Buck and Spitz demonstrate Buck's ability to rise above his challenges and adapt to survive in the harsh and brutal environment of the Klondike.
