Let me see if I can help with this one. This is a role question. We are asked specifically what role the first sentence play in the argument.
Let's take a look at the language of the first sentence:
"It is unreasonable to incarcerate anyone for any reason other than that he or she is a serious threat to the property or lives of other people."
So, it's unreasonable to do that. We need to ask ourselves, "Why?"...
The reason why, which is given in the following sentences, is supporting evidence. That makes the first sentence a conclusion. Whether or not it's well supported, or whether or not it's true, is not the point in question here. Rather, it's our job to recognize how the first sentence functions in relation to the rest of the stimulus, and because the information given in the first sentence is supported by the following sentences, that makes the first sentence a conclusion that was drawn by the author and supported by subsequent evidence. That makes C our answer. Hope that helps!
