PSAT Reading Question 511: Answer and Explanation

Question: 511

Which option gives the best evidence for the answer to the previous question?

• A. Lines 4–9 ("Of all . . . pathogen")
• B. Lines 18–20 ("The two . . . samples")
• C. Lines 32–38 ("Homeostasis . . . processes")
• D. Lines 44–49 ("One method . . . methanogenesis")

Correct Answer: A

Explanation:

(A) The correct answer is choice (A). These lines suggest that this species is helpful to humans rather than harmful because it has a very restrictive metabolism, meaning it's limited in its pathways. This is what's being shown by the two figures. Choice (B) is about the history of the discovery of methanogens in the gut. Choice (C) is a negative side effect of what can happen if the balance of methanogens isn't maintained, so it's about how they can be harmful to humans, rather than helpful. Choice (D) is about how homeostasis of the gut microbiota may be restored when it's disturbed. However, choice (D) is unrelated to the figures, as well as to how M. stadtmanae is beneficial to humans.