Answer:
O extremely close to death.
Step-by-step explanation:
"The Call of the Wild" by Jack London revolves around the story of Buck, a domesticated dog turned wild animal, and his adventures as a sled dog in the cold, Yukon mountains. The story follows Buck in his adventures through numerous masters and with John Thornton, one of the many gold miners.
In the given passage, the narrator describes how the sled dogs were so tired and deprived of enough food and rest. The dogs were "simply so many bags of bones in which sparks of life fluttered faintly." This spark faded and "seemed to go out, [except] when the club or whip fell upon them, the spark fluttered feebly up, and they tottered to their feet and staggered." These lines show that the dogs were extremely close to dying and the only thing that brings back life in them is the whip or the club on them.
Thus, the correct answer is the second option.