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 Luke Haqq
PowerScore Staff
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#76251
Hi destiny.ram!

To your question of how you can avoid making the mistake of eliminating the correct answer choice, I can suggest a couple things.

First, it's important to read the stimulus carefully; if one word like "prolonged" strikes use as an important one and decisive for eliminating answer choices, then I would make sure to go back to the stimulus, find that word, and confirm how it is being used. In this question, the word arises specifically in reference to "prolonged darkness." In terms of how to avoid mistakes, this is simply just a reminder about the importance of going back to the text and confirming specific citations (much like one would do for questions in reading comprehension that ask about the use of a specific term and provide a line reference for where it occurs).

Second, it's also important to be in a habit of diagram conditional reasoning when you encounter it. Related to this, the next step of making inferences based off of that conditional reasoning can also be critical to honing in on the right answer, rather than accidentally eliminating it. Here, we are told, "Without the prolonged darkness, followed by exposure to sunlight, the seeds do not germinate." To diagram this, note that it's helpful to apply PowerScore's method for conditional reasoning involving words like "unless," "without," and similar words. Whatever variables are modified by that word become the sufficient condition (left of the arrow) and the remainder is negated and is placed as the necessary condition (right of the arrow). This would produce:
seeds germinate :arrow: prolonged darkness AND subsequent sunlight exposure
In other words, if seeds germinate, then this means there was both prolonged darkness and sunlight exposure. In encouraging you to diagram conditional reasoning as well as inferences that can be made about it, taking the contrapositive is a great place to start. For the above statement, that would be:
prolonged darkness OR subsequent sunlight exposure :arrow: seeds germinate
In other words, if either prolonged darkness or subsequent sunlight exposure don't occur, then seeds won't germinate.

Having the above diagramming could help you arrive at answer choice (A) as the correct one. That answer choice reads, "Fewer pigweed plants will grow in the field if it is plowed only at night than if it is plowed during the day." Though the word "if" is tucked into the sentence rather than at the beginning, this is really just if-then conditional reasoning, which can be diagrammed as:
plowing only at night :arrow: fewer pigweed plants grow
Based on the conditional reasoning from the stimulus that we diagrammed, we know that this must be true. There would be fewer pigweed plants growing because there would be no subsequent sunlight exposure. The contrapositive shows why this is the case. One does not even need to get to the "prolonged darkeness" aspect part because we're already told from the question stem is asking about "a field [that] will be plowed in the spring and in which pigweed seeds have been buried in the soil all winter." The prolonged darkness is therefore a given, but we're missing the subsequent sunlight exposure. Without both of those, seeds won't germinate.
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 PresidentLSAT
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#89974
Hi Powerwcore,

Are we to assume that when plowing is done during the day, there is some exposure to prolonged darkness?
 Robert Carroll
PowerScore Staff
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#90131
President,

No need to assume! The question gives you the info that the seeds have been buried all winter, which is the prolonged darkness you're looking for.

Robert Carroll

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