During his voyage on the HMS Beagle, Darwin observed finches with different beak shapes. How did these observations contribute to his theory of evolution?

• A. They indicated that all finches descended from a single ancestor without variation.
• B. They showed the importance of genetic mutations in creating new species.
• C. They supported the idea of fixed species with no evolutionary change.
• D. They demonstrated the concept of adaptation to different ecological niches.

Answer: (D)