A．They can be used to deliver messages in times of emergency.
B．They deliver pollutants from the ocean to their nesting sites.
C．They carry plant seeds and spread them to faraway places.
D．They are on the verge of extinction because of pollution.

A．They migrate to the Arctic Circle during the summer.
B．They originate from Devon Island in the Arctic area.
C．They travel as far as 400 kilometers in search of food.
D．They have the ability to survive in extreme weathers.

A．They were carried by the wind.
B．They had become more poisonous.
C．They were less than on the continent.
D．They poisoned some of the fulmars.