Read the following text to answer questions 9 to 11.

    Tigers are members of the cat family. Lions, leopards, cheetahs, and house cats are also members of the cat family. Tigers are the largest cats, and the only cats with stripes. They live in large forest in southern and southeastern Asia. A tiger's short fur is usually dark orange with black stripes. Each tiger has different stripes, and you can use them to tell tigers apart. The stripes make a tiger stand out if you see them in the open. In the forests where tigers live, however, the stripes make them almost invisible. 

    Like house cats, tigers have soft pads bottoms of their paws. These allow to move silently through the forest. have long, sharp claws at the end of feet. They pull the claws in until they need them. When needed, the claws pop out like knives. 

    Their big, yellow eyes give tigers sight to help find prey. Tigers see as well as people during the day, and much better than people at night. They also hear well. They can turn their ears toward sounds. Tigers have explosive speed. 

    They have strong muscles and long legs that help them move extremely fast over short distances. Their long tails give them balance while running fast. Tigers have powerful jaws and sharp teeth. They help tigers grab and kill prey once they catch it.

"Each tiger has different stripes and you can use them... " (Paragraph 2). The underlined word refers to ....