Read the following short paragraphs and determine what type(s) o

Read the following short paragraphs and determine what type(s) of support is/are used in each to back up the conclusion of the paragraph. Are the support and the conclusion logically linked? If not, please make appropriate changes.
People need to improve their understanding of how language works so that they can use it more effectively. Research studies show that the study of a foreign language improves our understanding of the structure of language, providing a means of comparing different language structures. Therefore, people who speak only one language should be encouraged to study a second language.
【正确答案】：Authoritative testimony