单项选择题

Judging from the context, the word "they" (line 2, Para.4) refer to ______.

A．the security risks
B．the terrorist attacks
C．environmental hazards of over-centralization
D．the security risks, economic expenses, and environmental hazards

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单项选择题

According to the author, the most active advocates of Telecities are ______.

A．leaders and planners
B．urban architects
C．some corporations
D．government administrators