This question gave me pause so I will go over why each answer is wrong, spending the most time on B and D, the two serious contenders for this question. Here we are asked to go over what the main point of one of the paragraphs of the passage is, and if you have a pretty good working of PEAR this might be self evident, but it is one of those "is that just too easy?" questions.
A. while the first sentence states that it is more popular, the paragraph does not present an argument supporting why legal positivism is more popular, and this is largely ignored after the first line. Out.
C. Consensus is talked about at length, but the paragraph does not frame it as the focus--it isn't in the first sentence (which doesn't always mean its not involved but can be a strong indicator to look more closely), and is first mentioned as a way of specifying a point Dworkin is making about legal positivism. If consensus is only there to support a larger argument within the paragraph, it can't be the main point of the paragraph.
E. This particular paragraph is neutral about legal positivism--it merely specifies a point that Dworkin makes regarding legal positivism and provides a larger context for what legal positivism is.
B. This is at first possibly appealing because legal positivism is a part of the main focus--and it goes in to an explanation of jurist disagreement, but as pointed out in my explanation for E, it stays neutral on positivism. The third paragraph offers an evaluation of legal positivism's consensus in the first sentence.
D. If you paused and evaluated each paragraph while you read the passage, this would be an easy answer to prephrase. A summary of the second paragraph would be "explains legal positivism," or even, "explains legal positivism in a larger context and explains Dworkin's interpretation of legal positivism's approach in the face of disagreement among jurists" though this is a bit too in depth for a brief outline under time constraints.