Answer: B) By far the larger part of the slaves know as little of their ages as horses know of theirs, and it is the wish of most masters within my knowledge to keep their slaves thus ignorant.
Step-by-step explanation: From the given options the one that best supports the idea that slaves are no better than animals is option B, where the speaker explains that the most part of the slaves don't know their ages at all, and comparing their knowledge of their ages, to the knowledge horses have of theirs. And also emphasizing the fact that most masters want to keep slaves absolutely ignorant.