听下面一段独白，回答以下小题。
【小题1】Why does the speaker use the headphone to communicate with the listeners?

A．It is comfortable to use.

B．The listeners talk aloud.

C．The sound of the plane’s engine is loud.

【小题2】What is the cause of the dark sky?

A．The night time.

B．The thick clouds.

C．The black smoke.

【小题3】Which side of the island are the forests in?

A．The north side.

B．The west side.

C．The south side.

【小题4】What is the talk mainly about?

A．Having a ride in a plane.

B．Learning about a volcano.

C．Taking photos of forests.