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. According to the woman, what may limit the use of the material in cars
A．The high temperatures required for its use. B．The high cost of materials used in its production. C．The lack of trained environmental engineers. D．The opposition of automobile manufacturers.