Answer: a. Such a class you must have, or you would not have that other class which leads progress, civilization, and refinement.
Explanation: An analogy is a comparison between the features of two or more things, analogies are often used to help explain a point the view or an argument about any topic. In the given excerpt from James Henry Hammond’s speech “Cotton Is King” the piece of text that uses an analogy to justify the existence of the institution of slavery is the one from option a, it compares the "class" of slaves with the progress, civilization and refinement.
D Jupiter should be capitalized because it's the name of something.
The passage is centered on the theme of belonging in a certain pack or group. Buck may be a bit different from the others but as Buck tried to be like them and did what they usually do, it gathered the trust of the pack especially the leaders. To belong in a group, one should gain their trust.