5.2 Highlight the letter of the topic sentence in this paragraph.
5.2 a. There are two primary approaches to learning a foreign language. b. First, there is the textbook, approach of understanding the grammar and linguistics while studying vocabulary. c. Second, there is immersion in a foreign language, either in a school or in a foreign country where the language is spoken. d. Ideally, learning a foreign language involves a combination of both methods.