Read the following passage and choose the item (a, b, c, or d) that best answers each of the questions about it.
Although 80% of Australians live near cities, the cities are not as large as those in some other countries. Most people live in houses in suburbs - not in apartments. The suburbs usually have their own churches, schools, and shopping centers. They also have recreational facilities. In large cities, like Sydney, the suburbs are often far from the center of town. Because many people commute to work, traffic is slow and there are many traffic jams.
recreational (adj): (thuộc) sự giải trí
commute (v): đi làm xa
What does the word ‘their’ in line 3 refer to?
cities countries houses suburbs