Question 71·Medium·Command of Evidence
Marine biologist Dr. Lian Chen published a report on the state of coral reefs in the Indo-Pacific. In a geography essay, a student argues that Chen’s report demonstrates that the ecological condition of coral reefs has a direct impact on the economic well-being of nearby coastal communities.
Which quotation from Chen’s report would best support the student’s argument?
For command-of-evidence questions like this, start by rephrasing the claim in your own words and identify the two or three key ideas it contains (here: reef health, economic impact, nearby communities). Then quickly scan the answer choices and cross out any that don’t mention all the key parts. Be especially wary of choices that are only background facts or descriptions of methods; the correct evidence will usually show a clear, specific link (often with data or cause-and-effect language) between the situation described in the claim and a measurable outcome.
Hints
Focus on the key parts of the student’s claim
Underline the phrases “ecological condition of coral reefs”, “direct impact”, and “economic well-being of nearby coastal communities.” Look for a quotation that touches all of these ideas.
Look for both environmental and economic details
Ask yourself: which option talks not only about reef health but also about money, jobs, or resources used by people, such as fish catches or commercial activity?
Eliminate purely scientific or background statements
Cross out any choices that only describe temperatures, numbers of reefs or islands, or research methods without mentioning how people in nearby villages or towns are economically affected.
Step-by-step Explanation
Restate the student’s claim in simple terms
The student argues that Chen’s report shows a cause-and-effect link:
- Cause: the ecological condition (health) of coral reefs
- Effect: the economic well-being (financial situation, livelihoods) of nearby coastal communities
So we need a quote that connects reef health to economic outcomes for people living nearby.
Identify what the correct evidence must include
To support this claim, the quotation needs to include both of these pieces:
- Something about reef health or ecological condition (for example, coral cover, bleaching, reef damage).
- Something about the economy of nearby people (for example, fish catches, income, jobs, commercial activity in villages or towns near the reefs).
Any option that has only scientific details about reefs or only general information, without an economic effect on local communities, will not fully support the student’s argument.
Test each option against those two requirements
Check each answer choice:
- Choice A talks about water temperature and stress in coral polyps—this is about reef biology only, not about people’s economic well-being.
- Choice B gives background numbers about islands and the share of the world’s coral reefs—this is geography and scale, not economics or community impact.
- Choice D describes the research methods used to document reef health—this explains how data were collected, but says nothing about economic effects on nearby communities.
Only one choice directly combines reef condition with an economic measure affecting nearby villages.
Select the quotation that links reef health and local economies
The best supporting evidence is the quotation describing how commercial fish yields fell by an average of 35 percent in villages within five kilometers of reefs where live coral cover had dropped below 10 percent. This sentence clearly connects poor reef condition (low live coral cover) with a negative economic outcome (reduced commercial fish yields) for nearby coastal communities (villages within five kilometers), so the correct answer is:
“A 2019 survey of six Indonesian islands revealed that commercial fish yields fell by an average of 35 percent in villages located within five kilometers of reefs where live coral cover had dropped below 10 percent.”