What does the figure of speech butterflies in her stomach reveal about Nadia? A) that Nadia has an unusual medical condition in which small butterflies live in her stomach B) that Nadia is extremely nervous about performing her piano routine in the school talent show C) that, while Nadia loves her dog Lucky, she has an allergic reaction to his being too close to her D) that Nadia is confident about her skill as a pianist and can't wait to perform in the school talent show