Here's a problem to solve: Researchers recently discovered a gene in humans that previously was unknown to science. Which statement best explains why the gene probably was not discovered much sooner?

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

- A: The gene only recently evolved in humans.
 
- B: The technology used to study genes is still being developed.
 
- C: Scientists were not interested in genes until a few years ago.
 
- D: Scientists were sure they had already discovered every possible gene.
 