Read the excerpt from The Call of the Wild.

Then an old wolf, gaunt and battle-scarred, came forward. Buck writhed his lips into the preliminary of a snarl, but sniffed noses with him, Whereupon the old wolf sat down, pointed nose at the moon, and broke out the long wolf howl. The others sat down and howled. And now the call came to Buck in unmistakable accents. He, too, sat down and howled. This over, he came out of his angle and the pack crowded around him, sniffing in half-friendly, half-savage manner. The leaders lifted the yelp of the pack and sprang away into the woods. The wolves swung in behind, yelping in chorus. And Buck ran with them, side by side with the wild brother, yelping as he ran.

Which theme does this passage illustrate?

Good leaders are strong, intelligent, and treat their followers well.
Only the strong survive in the wilderness.
The only way to learn something is to try it.
The desire to fight for power is a natural instinct.

Only the strong survive in the wilderness.

The theme that this passage illustrates is "Only the strong survive in the wilderness." This is evident through the description of the old wolf, who is described as gaunt and battle-scarred, and the howling and running together as a pack. The passage emphasizes the survival instincts and the need to be strong and capable in order to thrive in the harsh environment of the wilderness. To determine the theme, one can analyze the actions and descriptions provided in the passage and consider the underlying message conveyed by the author.

The theme illustrated in this passage is: Only the strong survive in the wilderness.