单项选择题
In Sections A, B and C you will hear everything once only. Listen carefully and then answer the questions that follow.SECTION A TALK Questions 1 to 5 refer to the talk in this section. At the end of the talk you will be given 15 seconds to answer each of the following five questions. Now listen to the talk.
Why did the early cities fail to grow as quickly as expected throughout the 18th century（） A．Because the countryside attracted more people.
B．Because cities did not increase in number.
C．Because the functions of the cities changed.
D．Because the number of city people was stable.