In this section you will hear several conversations. Listen to the conversations carefully and then answer the questions that follow. Questions 1 to 4 are based on the following conversation. At the end of the conversation, you will be given 20 seconds to answer the questions. Now listen to the conversation. What is the new material
A．A fuel that burns cleanly. B．An oil additive that helps cool engines. C．A material from which filters are made, D．An insulating material sprayed on engine parts.