1) The question here implies that the dogs are exhausted and are operating on autopilot for their master/whomever is doing the whipping. You can see this when the writer says:
"When a halt was made, they dropped down in the traces like dead dogs, and the spark dimmed and paled and seemed to go out"
Consequently, when the whip is used, the dogs momentarily spring back into life. We can see this when the author writes:
"And when the club or whip fell upon them, the spark fluttered feebly up"
The key here is the word "feebly".
Whilst the dogs do indeed exhibit a spark of life, they do so feebly or without energy.
The answer to your first question is B) how exhausted the dogs are.
2) When looking at this question, the first answer seems to provide you with the answer you're looking for. The dogs are clearly very close to death. The spark which refers to the life force powering the dogs forward, is feeble and will not last much longer.
What's more, the passage states that the dogs "tottered" and "staggered".
These are both actions of tired beings.
The answer to your second question is B) extremely close to death.
