hi stephen, this excerpt and question are not from an official sat, but intended to model a new sat question. i would argue that the sat uses “real-word texts” on the test, and since real world texts are not always perfectly organized, this could potentially be a paragraph from an sat passage. however, it is taken a bit out of context since we do not have the entire passage here. students on the sat would have the benefit of seeing the entire passage and the sat would expect them to answer a question like this in the context of that entire passage. so the last sentence may be leading into the following paragraph, and with the context of the entire passage, students might be able to more easily see what the function of this paragraph is. regardless, as far as the sat is concerned regarding wrong answers, “main ideas” need to be evident in more than just one sentence, so c wouldn’t be correct. hope that is helpful context!