Elijah has these thoughts about Buck after reading The Call of the Wild. 1. When Buck is beaten by his new owners, he learns that he must sometimes stop fighting if he wants to survive.
2. When Buck witnesses Curly get killed by the other dogs, he learns that once you go down, it is almost impossible to get back up.
3. Buck learns that he must first kill Spitz (before Spitz kills him) if he wishes to survive.
4. Buck learns that he must sometimes steal and deceive in order to get the food he needs to survive.

Based on these thoughts, which thesis statement would be most appropriate for a literary analysis of themes within the novel?

Based on what happens to Buck within The Call of the Wild, a major theme within the novel is "only the strong and smart survive the wilderness." I agree with this theme.
Buck must learn to adapt with each new lesson he learns within the wild. This makes "only the strong and smart survive the wilderness" a major theme within The Call of the Wild.
In The Call of the Wild, Buck faces many challenges. These challenges show that "only the strong and smart survive the wilderness," and this is a major theme of the novel.
Clearly, as evidenced by events within the passage, a major theme of The Call of the Wild is "only the strong and smart survive the wilderness." Buck learns this lesson the hard way.