His discoveries on the islands were paramount to the development of his Theory of Evolution by Natural Selection.
On the islands, Charles Darwin discovered several species of finches.
Thanks to his close observations, he discovered that the different species of finches varied from island to island.
ITS D I THINK PRETTY SURE BUT DO TAKE MY WORD FOR IT.
"The mouth" is the correct answer
One of them is smaller, because the moon is much closer to earth than the sun.
Think of the moon orbiting the earth as a smaller version of the earth orbiting the sun.