Read the academic passage below and identify the sentence that performs the specified rhetorical function.
Answer:[Sentence 1] For decades, paleoclimatologists assumed that oxygen isotope ratio () fluctuations in speleothem calcite from East Asian caves reflected linear variations in absolute summer monsoon precipitation amounts.
[Sentence 2] However, recent high-resolution modeling of atmospheric vapor transport suggests that these isotopic signatures are dominated instead by upstream rainout kinetics and moisture source origin rather than local rainfall volume.
[Sentence 3] To evaluate this competing hypothesis, Dr. Arisawa analyzed trace element ratios () alongside isotope profiles across three distinct glacial-interglacial transitions, expecting that localized moisture markers would decouple from isotope anomalies if rainout kinetics predominated.
[Sentence 4] Surprisingly, while trace element shifts did mirror localized hydrology, the signals exhibited an abrupt, synchronized shift prior to any regional hydrological transition.
[Sentence 5] This discrepancy demonstrates that while values cannot be treated as a simple proxy for local rainfall, they nevertheless record broad planetary-scale circulation reorganizations that precede regional climate responses.
In the passage above, the sentence that explicitly describes an empirical procedure established to test the validity of the alternative model is Sentence 【3】.
[Sentence 2] However, recent high-resolution modeling of atmospheric vapor transport suggests that these isotopic signatures are dominated instead by upstream rainout kinetics and moisture source origin rather than local rainfall volume.
[Sentence 3] To evaluate this competing hypothesis, Dr. Arisawa analyzed trace element ratios () alongside isotope profiles across three distinct glacial-interglacial transitions, expecting that localized moisture markers would decouple from isotope anomalies if rainout kinetics predominated.
[Sentence 4] Surprisingly, while trace element shifts did mirror localized hydrology, the signals exhibited an abrupt, synchronized shift prior to any regional hydrological transition.
[Sentence 5] This discrepancy demonstrates that while values cannot be treated as a simple proxy for local rainfall, they nevertheless record broad planetary-scale circulation reorganizations that precede regional climate responses.
In the passage above, the sentence that explicitly describes an empirical procedure established to test the validity of the alternative model is Sentence 【3】.
Answer
Sentence 3 is the correct sentence because it explicitly outlines the empirical investigation (analyzing trace element ratios alongside isotope profiles) undertaken specifically to evaluate the newly proposed competing hypothesis.
Sentence 3 directly fulfills the specified function. It opens with the infinitive phrase 'To evaluate this competing hypothesis,' signaling that the subsequent clause—detailing Dr. Arisawa's analysis of trace element ratios () alongside isotope profiles—describes the specific empirical test established to evaluate the alternative model introduced in the preceding sentence.
Step-by-Step Solution
Key Concept
Rhetorical Role and Sentence Function Identification in Dense Scientific Argumentation
Estimated Time:2m 0s