Questions 4 to 7 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
Finally, the customer chose the hat made of ______.

A．There would be a disciplinary commission.
B．Ten Australian athletes had been tested.
C．The result of the test was positive.
D．This test was a blood on

A．for
B．on
C．with
D．into