<span>There are a few ideas at play here. Firstly the Grey Ghost recalls their own Boo Radley. Like Radley the character of Stoner's boy was misjudged. Secondly the character, like Boo Radley, turns out to be a hero.</span>
In the first sentence, hurdle is used as something that runners are jumping over/a physical objects. This means it is being used to represent “barrier”.
In the second sentence, a difficulty/challenge is being described. Therefore, hurdle here is used to mean “problem”.
Answer:
A. The references to chronic sleep deprivation and persistent sleepiness in paragraph 2
Explanation:
The textual evidence that best supports the inference that sleep deprivation is more than an occasional health problem for students is the reference in paragraph 2 of the publication that linked chronic sleep deprivation to persistent sleepiness.
Maybe a or b. I believe that both fit the question. Hope it helps! :) :) :)