tkorzhan18 wrote:
GMATNinja, why ants that don't use pheromones should be in scope in this argument?
(I did not select C because I assumed ants should always use pheromones on their way from nest to food source. As a result of bringing additional info that Ants don't use pheromones, we are contradicting evidence noted in the argument. )
In this question, we are looking for the answer choice that is "most strongly supported" by the statements above. Let's consider (C):
Quote:
(C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.
Based on the passage, "pheromones evaporate without a trace almost immediately when temperatures rise above 45 degrees Celsius (113 degree Fahrenheit), as is typical during afternoons in places such as the Sahara Desert." So
if ants left a trail of pheromones when temperatures were above 45 degrees Celsius, the pheromones would "evaporate without a trace."
In this situation, therefore, ants would not be able to use pheromones to "guide themselves between food and their nest." As a result, we can safely conclude that IF any ants live in the Sahara Desert, and IF they forage for food at no time but the afternoon, they would "generally not use pheromones to guide themselves between food and their nest," since we know the pheromones would likely evaporate. As a result, (C) is correct.
In your reasoning, it sounds like you "assumed ants should
always use pheromones on their way from nest to food source." But keep in mind that the passage only states that "
most species leave a trail of chemicals called pheromones." This means that
some species of ants may not use pheromones. So, the evidence is consistent with the possibility that some species of ants may not use pheromones.
Additionally, note answer choice (C) is not actually stating that ants live in the Sahara Desert, or that they forage for food at no time but the afternoon. It's simply saying that IF they did, they would generally not use pheromones to guide themselves between food and their nest. And because we know that pheromones "evaporate without a trace" at temperatures above 45 degrees Celsius, this statement is supported by the evidence.
I hope that helps!