Questions 11 to 13 are based on the following announcement. At the end of the announcement, you will be given 15 seconds to answer the questions. Now, listen to the announcement. Scientist Sir John Vane shared the Nobel Prize in Medicine partly because______.
A．he found how to produce aspirin B．he first made aspirin into its present pill form C．he was the first to use aspirin on patients D．he discovered how aspirin works