ASVAB Paragraph Comprehension Practice Test 461525

Question 4 of 5
In linguistics, the comparative method is a technique for studying the development of languages by performing a feature-by-feature comparison of two or more languages with common descent from a shared ancestor, as opposed to the method of internal reconstruction, which analyzes the internal development of a single language over time.
Which of the following would be the most useful for someone using the comparative method in linguistics when studying a particular language?
An ancient text written in the language.
The same text written in two different dialects of the language.
Old folk songs that have been passed down among generations of speakers of the language.
Two editions of the same text written one-hundred years apart.