Questions 11 to 13 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now, listen to the passage. Which of the following do you think is true, according to the speaker

A．The speaker believes bicycling can solve the problem of traffic completely.
B．The speaker thinks that bicycling can solve the problem of economy entirely.
C．The speaker assumes bicycling can solve the problem of pollution completely.
D．The speaker doesn’t believe bicycling can solve the problem of traffic entirely.