"Tan enjoys thinking about language and using different forms of English" is the option that best summarizes the central idea of the excerpt. (option D)
What is a central idea?
We can define central idea as the underlying message of a literary work, that is, the message the author wants to convey to the audience. In the paragraph from "Mother Tongue" that we are analyzing here, the central idea is that Tan enjoys thinking about language.
Tan explains she is a writer and quite fascinated by everything language has the power to do. She says she can "spend a great deal of [her] life thinking about the power of language."
With the information above in mind, we can choose option D as the correct answer.
Learn more about central ideas here:
https://brainly.com/question/1914191