Which excerpt from The Call of the Wild shows both a beginning and an end to an episode in Buck’s life?

This was the first time Buck had failed, in itself a sufficient reason to drive Hal into a rage. He exchanged the whip for the customary club. Buck refused to move under the rain of heavier blows which now fell upon him. Like his mates, he was barely able to get up, but, unlike them, he had made up his mind not to.
Dog and man watched [the sled] crawling along over the ice... They saw Charles turn and make one step to run back, and then a whole section of ice gave way and dogs and humans disappear. A yawning hole was all that was to be seen.
This man had saved his life, which was something; but, further, he was the ideal master... he saw to the welfare of his [dogs] as if they were his own children, because he could not help it.
Buck had a trick of love expression that was akin to hurt. He would often seize Thornton’s hand in his mouth and close so fiercely that the flesh bore the impress of his teeth for some time afterward.