Free SAT Practice Question

Question 1 of 1
ID: DSAT-RW-57
Section: Digital SAT Reading & Writing (RW) - Broadly Reading - Craft and Structure
Topic: Text Structure and Purpose
Difficulty level: Hard

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In ecological studies of coral reef systems, scientists have long observed that reef biodiversity is closely linked to the presence of grazing herbivores such as parrotfish and surgeonfish. These species maintain algal populations in check, thereby allowing coral larvae to successfully settle and grow. In systems where herbivorous fish are removed—whether through overfishing or habitat degradation—algal overgrowth can lead to phase shifts in which coral-dominated ecosystems are replaced by algal-dominated ones. This transition has been associated with significant losses in biodiversity and is notoriously difficult to reverse once established. Recent research has focused on whether targeted interventions, such as the reintroduction of herbivorous fish species or artificial reef construction, can restore coral dominance, but results remain inconsistent due to variations in local nutrient levels, water temperature, and human activity.

Which choice best describes the function of the underlined sentence in the passage as a whole?

AIt presents the ecological consequence of removing a key functional group from reef ecosystems, thus establishing the urgency behind the restoration efforts discussed later in the passage.

BIt introduces an exception to the typical relationship between herbivorous fish and coral reefs in order to suggest that other factors may play a larger role in reef decline.

CIt defines a common feature of coral ecosystems that remains stable across environmental conditions, thereby framing the need for future research mentioned later in the text.

DIt summarizes the long-term goal of coral reef studies by identifying a desired state of ecosystem balance that is expanded upon in the remainder of the paragraph.

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