Hi goingslow!
Happy to address those answer choices.
The question stem asks about "the purpose of passage A and the purpose of passage B, respectively." The two answer choices you mentioned are:
(A) persuade and inform
(E) advocate and deflate
Without considering the subject matter of either paragraph yet, if these were your two contender answers, it's worth noting what seems to be a key aspect that makes these answer choices quite different from one another. Namely, the verbs in answer choice (A) are both generally positive or at least neutral actions. In answer choice (E), by contrast, the two verbs seem far more in contrast to one another--e.g., attorneys "advocate" for their own clients while they might seek to "deflate" the opposition.
This seems worth noting because, if pressed for time, having a basic understanding of how the passages relate to one another (e.g., are they in agreement or disagreement, discussing the same or different subject matter, etc.) could be enough to get you to the right answer. If you gleaned that the passages were markedly different, for example, this would seem to lend support to answer choice (E).
And it proves to be the case in looking to the specific substance of the passages that they are quite different in tone and aim. Passage A is much more pro-markets in comparison with Passage B. For example, the former states in the first paragraph that "Markets, such as stock exchanges, distill the collective wisdom of millions of individuals into a single number ... What's more, markets reward people who are right." That paragraph also suggests these aspects of markets may be more reliable than "other information-gathering institutions, such as committees and polls."
Passage B, by contrast, starts out, "Markets are not infallible." This alone should make answer choice (E) a clear winner over (A) because it contrasts so sharply with Passage A. For a further example, the Iowa Electronic Markets project is mentioned in both passages--in Passage A it is used to attest to the virtues of markets in providing forecasts, whereas in Passage B the same project is mentioned in a more critical light.
(E) is the right answer because it suggests dissimilarity, and these passages indeed have very different perspectives from one another with respect to markets.
Hope that helps!