Here's a problem to solve: Pluto was discovered in 1930 and was named the ninth planet. In 2003, an object larger than Pluto was discovered by astronomer Michael Brown. Pluto has been reclassified as a "dwarf" planet. What does this most likely suggest about scientific investigations?

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

- A: Earlier scientists did not use appropriate tools.
 
- B: Pluto should not have been classified as a planet.
 
- C: Classifications change as new evidence is gathered.
 
- D: Review of planetary characteristics should occur every year.
 