Linguists studying neighboring mountain villages found that younger speakers' vowel pronunciations were more similar across villages than those of older speakers. Some linguists attributed this convergence to schools promoting the national pronunciation. Others argued that regular trade at a regional market had produced a pronunciation shared by the villages but not dictated by the national standard. Both processes could reduce differences among the villages. Only under the school-based account, however, would increasing agreement among the villages necessarily coincide with decreasing distance from the national norm. To assess the accounts, the researchers compared the direction of each village's vowel shifts with pronunciations in national broadcasts and in the regional market town.
Which choice best describes the function of the underlined sentence in the text as a whole?
For a function question involving competing explanations, first identify what both explanations predict and then determine what the underlined sentence says is unique to one of them. Pay close attention to logical terms such as “only,” “necessarily,” and “could,” and use the following sentence to determine how that distinction guides the researchers' next step.
Hints
Separate the predictions
Determine which result both accounts could produce and which additional result is required by only one account.
Track the logical wording
Consider the difference between evidence that an account requires and evidence that would conclusively eliminate every alternative.
Use the final sentence
Ask why the researchers need both national broadcasts and regional market speech as reference points.
Step-by-step Explanation
Identify the shared prediction
Both proposed processes could make pronunciations across the villages more similar, so convergence alone does not determine which account is better supported.
Interpret the necessary consequence
The phrase “only under the school-based account” indicates that movement toward the national norm is required by that account. The market-contact account predicts a shared regional pronunciation, which does not necessarily approach the national standard.
Connect the sentence to the comparison
The researchers compare the vowel shifts with national broadcasts and speech from the regional market town because those references help evaluate which proposed influence better accounts for the pattern. Thus, the underlined sentence supplies the logical basis for the comparison.