An "adaptation" is, by dictionary definition, "a movie, television drama, or stage play that has been adapted from a written work, typically a novel." Answer C, "a musical based on the life of a popular band," meets the definition of an adaptation.
The central idea is the same as the main idea. Most of the time, the main idea is mentioned in the Title. Without reading the essay, I do not know what the central/main idea is.
Readers can contrast what they “see” and “hear” when reading a written text with what they perceive while listening to or viewing an audio or visual version. The largest difference is the level of interaction that each medium requires from the audience.
