modified characteristic ecological succession structural adaptation selective breeding
I gave my students this multiple choice question: The fur color of a bear varies with its environment. Polar bears found in the Arctic have white fur, while black bears found in Pennsylvania have dark fur. Which best describes the variation of fur color amongst the bear species?

Only one answer is correct among these 4 choices:
- modified characteristic
- ecological succession
- structural adaptation
- selective breeding

Could you tell me which one is correct?

structural adaptation