Questions I to 4 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.
According to the conversation, what unique photographic technique did Margaret Cameron use

A．Because they didn’t understand their language.
B．Because they saw them as a source of threat to their jobs.
C．Because they were arrogant people.
D．Because they had very different appearances.

A．Electronic screening at the airports.
B．Upgrading counter-terrorism technology.
C．Increasing counter-terrorism budget.
D．Promoting cooperation with Americ