Black bears are very active during spring and summer but hibernate throughout the winter. They make their dens in enclosed spaces such
as rocky caves or hollow trees. In late autumn, a black bear scrapes together a nest of leaves and sticks in a den. Then the bear curls up in the nest
and falls asleep. While hibernating, the bear sleeps lightly, and its heart rate and breathing become much slower than normal. The bear does not
eat or drink while hibernating, and it loses about half of its weight. When spring arrives, the bear awakens and emerges from its den. For the next
few weeks, the bear does not eat very much, but during the summer the bear eats large quantities of food. The bear must fatten up before fall,
when it's time to hibernate again.
What is the purpose of the underlined sentence?
1. It compares the fall and winter activities of black bears.
O2. It explains why black bears hibernate during part of the year.
3. It describes how the process of hibernating begins for black bears.
O 4
It supports the idea that black bears are only active for part of the year.