Why might polar bears become extinct a. they do not have any predators b. they may drown when the glaciers melt c. their thick fur is not suited for a warming climate d. too many hurt them

They do have predators because of killer whales, although that is not the killer whale's only source of food.

They are good swimmers, however if all the glaciers melt then they would grow tired of swimming and would drown.

Polar bears fur is not suited for a warm climate, although they could survive for a while.

I would go with d. because all the answers are correct.

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.