How would you distinguish adaptations and variations for a younger student?

"Imagine a Polar Bear. You know they live in the Arctic, but then the Summer season comes. The polar bear has to move away from the breaking ice. Once the heat kicks in, the polar bear's warm fur makes it harder to survive. The bear has the ability to last in the heat for a long while, going back and forth into the water and land. After a while of doing this, the polar bear's fur becomes suited to the harsh light. Once Winter returns, the bear waits for the heat to fade and for the ice to form back. Once the ice is formed, the polar bear knows that its back to its old warm fur procedure."

b c a d mark me

the answer is b.) hydrogen bonds between bases.