Here's a problem to solve: A species of bird has not been seen since the 1900s and is considered extinct. Which evidence would best disprove the claim that the bird is extinct?

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

- A: A bird watcher makes a sketch of the bird.
 
- B: A scientist discovers fossil remains of the bird.
 
- C: A researcher takes a photograph of the bird.
 
- D: A park ranger finds a suitable habitat for the bird.
 