Consider the following multi-source information regarding coastal ecological restoration: … — GMAT

Consider the following multi-source information regarding coastal ecological restoration:

Tab 1: Research Proposal (Marine Ecology Institute)
Dr. Thorne proposes planting macroalgae kelp near coral reefs in Sector B to mitigate ocean acidification. Dr. Thorne argues that kelp photosynthesis reduces dissolved carbon dioxide ( $CO_2$ ), thereby directly raising seawater pH and protecting coral calcification rates.

Tab 2: Environmental Monitoring Data (Sector B)
| Location | Kelp Density ( $g/m^2$ ) | Dissolved $CO_2$ ( $ppm$ ) | Seawater pH | Coral Calcification Rate ( $mg/cm^2/day$ ) |
| Sector B1 | 450 | 340 | 8.15 | 1.8 |
| Sector B2 | 120 | 410 | 7.95 | 1.1 |
| Sector B3 | 480 | 405 | 7.96 | 1.2 |

Tab 3: Oceanographic Study (Hydrodynamics Bulletin)
Sector B3 undergoes intense seasonal upwelling, drawing deep ocean water high in dissolved $CO_2$ to the surface. The high nutrient levels in upwelled water drive rapid kelp growth in B3, but the inflow of $CO_2$ far exceeds the carbon absorption capacity of the kelp population.

Statement to evaluate:
Evaluating the data from Sector B3 alongside Sector B1 weakens Dr. Thorne's argument that high kelp density is sufficient to increase local seawater pH.

Answer: Answer

Answer

True. Integrating the observational data from Tab 2 with the oceanographic findings from Tab 3 reveals that Sector B3 has the highest kelp density (

480\text{ g/m}^2

) yet maintains a depressed pH level (

7.96

) because upwelled

CO_2

exceeds the absorption capacity of the kelp. This proves that kelp density is not sufficient by itself to ensure elevated seawater pH, directly weakening Dr. Thorne's argument.

The statement is true because cross-tab synthesis of Tab 2 and Tab 3 demonstrates that high kelp density in Sector B3 coincides with low seawater pH (

7.96

) due to heavy

CO_2

upwelling that exceeds biological uptake. Comparing B3 to B1 invalidates the premise that kelp planting alone is sufficient to increase localized pH.

Step-by-Step Solution

Identify Dr. Thorne's central argument in Tab 1.

Dr. Thorne asserts that planting kelp absorbs dissolved

CO_2

, which raises local seawater pH.

Establishing the claim is required before determining whether multi-tab evidence strengthens or weakens it.

Compare monitoring data across Sector B1 and Sector B3 in Tab 2.

Sector B1 has kelp density

450\text{ g/m}^2

CO_2

level

340\text{ ppm}

, and pH

8.15

. Sector B3 has higher kelp density (

480\text{ g/m}^2

), higher

CO_2

(

405\text{ ppm}

), and lower pH (

7.96

Evaluating whether higher kelp density correlates with higher pH across locations tests the sufficiency of kelp for raising pH.

Synthesize Tab 2 data with the contextual oceanographic mechanism in Tab 3.

Tab 3 explains that upwelling in B3 supplies nutrients for kelp growth but introduces

CO_2

in volumes exceeding kelp uptake. Thus, kelp presence cannot counteract the

CO_2

influx to raise pH in B3.

Combining cross-tab evidence reveals that high kelp density is insufficient to guarantee high pH when unmitigated carbon inputs exist, thereby weakening the proposed intervention's underlying claim.

Key Concept

Evaluating Argument Support and Weakening Across Tabs

Estimated Time:1m 30s

Question

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