Many years ago, polar bears had vast areas of sea ice to hunt seals, their primary food source. They easily travelled long distances and found plenty of food. Now, due to global warming, the sea ice is melting rapidly. This change makes it much harder for polar bears to hunt, and they often struggle to find enough food for survival.
What is the present challenge for polar bears, according to the text?
A) They have too many predators.
B) They cannot find enough food due to melting sea ice.
C) They prefer different types of food now.
D) They are moving to warmer climates.