What is the underlying theme of this passage?

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.
(from the call of the wild by jack london)
isolation from brethren
honor of battle
beauty of nature
deep instincts
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Read the paragraph. theodore roosevelt was the greatest president because as a leader of the progressive party, he brought about much-needed social, political, and economic reform. one of his economic reforms was to break up many large business trusts. by doing so, he took economic power out of the hands of the wealthy and powerful corporations and placed it in the hands of the ordinary people. theodore roosevelt’s reform policies, known as the square deal, to give the average citizen an equal share of opportunities. which sentence is the thesis of this paragraph? theodore roosevelt was the greatest president because as a leader of the progressive party, he brought about much-needed social, political, and economic reforms. one of his economic reforms was to break up many large business trusts. by doing so, he took economic power out of the hands of the people and placed it in the hands of the ordinary people. theodore roosevelt’s reform policies, known as the square deal, to give the average citizen an equal share of opportunities.