Question

question #2
heavy monsoon rains overwhelmed low-lying basins, displacing over twenty million people in southeast asia. in one region, unusually persistent rainfall was followed by dam mismanagement and tide-locked drainage systems—causing retention canals to overflow for weeks. urban districts built atop concrete fill suffered disproportionately because not only did the impervious concrete reduce soil absorption, the undermaintained levees also gave way under sustained pressure. in contrast, rural floodplains experienced slower inundation and proved more resilient.

which choice best describes the function of the underlined text?
a) it reinforces the argument that infrastructure vulnerability is inevitable in urban areas.
b) it introduces a speculative interpretation that is refuted in the next sentence.
c) it states a causal relationship that elaborates on the impact of a natural phenomenon.
d) it contrasts against a more effective solution that leads to fewer problems in most cases.

Explanation:

The underlined text ("not only did the impervious concrete reduce soil absorption, the undermaintained levees also gave way under sustained pressure") explains why urban districts suffered disproportionately: two factors (impervious concrete, undermaintained levees) caused worse flooding, elaborating on the impact of the monsoon rains (natural phenomenon). Option A is incorrect because it claims inevitability, which isn’t stated. Option B is wrong as no speculation is refuted. Option D is incorrect because no "more effective solution" is mentioned.

Answer:

C) It states a causal relationship that elaborates on the impact of a natural phenomenon.