Please answer the following question: Mary likes to invent things. She creates a new language and teaches it to her friend, Jean. Mary and Jean like to talk to each other in their own language because they think no one understands them and it is funny. When they go shopping, they say things like: "Look! He is fat." "This CD is awful." "I want to eat free hamburgers." A clerk comes but he can't understand what they say. He asked them: "May I help you?" Mary and Jean just laugh. What fun it is to create something new. What do they do in the store? A) They buy some things. B) They talk with the clerk. C) They want to understand what people say. D) They use their new language and talk about people and things.
A:
D