Which of the following is the hook?
1: Over the years deep sea creatures have adapted to most conditions in the ways
explained above. Without adaptations like these, many deep-sea creatures would
have become extinct.
2: According to recent studies, "Squid have eyes that are 30 cm in diameter, eyes
larger than most deep sea animals, which have great light absorbing capacity"
("Giant Squid").
3: While awareness of predators is very important, deep-sea creatures also need to
adapt to their environment.
4: It is very hard for deep sea creatures to survive under water. With elements such
as extreme darkness and temperatures that can reach 700F in some areas,
these creatures must adapt to such conditions over time.