Here's a problem to solve: In some U.S. national parks, black bears have lost their fear of humans and look for food near campsites along the roadside. This is an example of an animal

Among the 4 following options, which is the correct answer?

- A: becoming an herbivore.
 
- B: using its inherited traits.
 
- C: finding a new ecosystem.
 
- D: learning a new behavior.
 