Question

the cygnus flume lichen is native to northern european forests, where the moth, agonopterix heracliana, feasts on its tissues. the lichen found its way to north america in 1840, a geographical zone devoid of any agonopterix heracliana. however, the intricate web of predator and prey relationships is known to survive the test of time and geographic shift. in 2020, the moth was detected in the northeast of north america, where botanist haruki tanaka and his team were studying the lichen. astonishingly, within a year, 87% of the cygnus flume lichen populations were found to be infested by the moths.
9
which choice best describes the function of the third sentence in the overall structure of the text?
a it lays out the theory that tanaka and his colleagues aimed to examine, using cygnus flume lichen and agonopterix heracliana.

b it proposes a broad principle that is evidenced by the interaction between cygnus flume lichen and agonopterix heracliana.

c it suggests an alternate explanation for the observations of tanaka and his colleagues.

d it delivers context that illuminates why the organisms in question moved to unfamiliar territories.

Explanation:

• Option A: The third sentence doesn't lay out a theory Tanaka aimed to examine. Tanaka was studying the lichen, and the third sentence is a general principle about predator - prey relationships, not related to Tanaka's study aim.
• Option B: The third sentence states a broad principle (predator - prey relationships survive time and geographic shift). Then, the interaction between the lichen and the moth (moth arriving in North America and infesting the lichen) serves as evidence for this principle. This matches the function of the third sentence.
• Option C: The third sentence doesn't suggest an alternate explanation for Tanaka's observations. It's a general principle, not an explanation for their findings.
• Option D: The third sentence is not about why the organisms moved to unfamiliar territories. It's about the durability of predator - prey relationships.

Answer:

B. It proposes a broad principle that is evidenced by the interaction between Cygnus flume lichen and Agonopterix heracliana.