I personally find this the hardest LR question in PT 14; it is (1) bizarre on the level of content, (2) very long and overloads test takers with information, and (3) at the very end of the fourth section, thus hitting you at a point of the test where you already spent 2+ hours intensively thinking about stuff and are mentally exhausted.
In paraphrased form, the stimulus says:
(1) Phenomenon: In the Peruvian desert, there are different sets of lines in the sand. These lines occur in different layers: On the top layer, there are lines that branch out from a single point. Beneath that, there are lines that form a bird figure.
(2) Hypothesis: An investigator argues for the conclusion that both of these sets of lines were brought about by aliens, who supposedly used the Peruvian desert to land their space ships. To support this conclusion, the investigator evokes the premises that the lines in the sand would have been useless to Incas.
The first thing to do here is to figure out what the stimulus is even about: The phenomenon itself is not immediately clear – it is crucial to note that there are TWO sets of lines, not just one –, and the investigator’s hypothesis is counterintuitive to a degree that it becomes all too easy to disregard the glaring selective attention fallacy in their reasoning (Aliens or Incas, not Incas; therefore aliens). So the first hurdle here is to even figure out what is going on, and to throw out one’s common sense intuitions out of the window (How can you even identify the different layers of ancient lines in the sand? How did the lines stick around for so long? All of these questions become irrelevant).
The next hurdle then is the question stem, which again seems bizarre: Here, the test writers tell us that we seek to establish the conclusion that the lines are supposed to refer to astronomical phenomena, and that we are supposed to block an alternative hypothesis to the effect that the lines are non-astronomical. So at this point this seems to become a sort of strengthen question. The question stem is unusual to an extent that it becomes hard to pre-phrase or anticipate how a right answer might look like. Thus process of elimination seems to be the best approach:
(A) North American natives arranged stones in ways that allow for the measurement of astronomical phenomena. This seems to strengthen a little bit in that it points out a seemingly analogous case (It is not only in South America but also in North America that people used geological means to keep track of astronomical phenomena). However, it seems unclear how this answer choice would also have the blocking effect that the question stem is asking for. Thus keep around as a candidate but expect that one of the other answer choices might well be better.
(B) The straight lines indicate positions at which astronomical events could have been observed ‘at plausible dates,’ and the bird lines could represent a constellation. This gets at both sets of lines and associates both of them with astronomical phenomena. The answer thus is fairly specific. Furthermore, the answer itself postulates its own plausibility (‘plausible dates’), which seems like a massive hint, though again unusual. Like the rest of this question, (B) thus again seems wildly counterintuitive, but in the scenario we are supposed to explain, (B) arguably makes the most sense. In particular, (B) approximates the desired function more than (A). Thus far this thus is the least bad answer choice.
(C) The lines form patterns. This answer choice is worse than (B), due to its lack of specificity and its apparent disconnect from the question stem. Worst answer choice thus far.
(D) Central American Natives used rocks to measure astronomical phenomena. This answer choice seems almost identical to (A) and thus provides good grounds to dismiss both (A) and (D): There can only be one correct answer choice, two virtually identical answer choices thus are likely to both be false.
(E) The bird lines might be older than the straight lines. Again irrelevant; (B) must be right.
Takeaways: This seems to be a question where the LSAT really tries hard to make test takers focus exclusively on reasoning structures, not on common sense intuition or plausibility. In this sense, the question is similar to other early LR questions that seem weird content wise but make syntactical sense on the level of formal logic. Focus on getting a clear understanding of what is going on in the stimulus and the question stem; I spent four minutes on this and still felt overwhelmed. Get a clear grasp of what the phenomenon is, what the explanation attempt from the stimulus is trying to say, and how the two alternative explanatory directions from the question stem relate to another. Then use process of elimination to get through the answers.
