Charles darwin viewed the fossil record as

A) evidence that earth was a thousand years old - I know it isn't this one

B) Useful support for his theory - I'm leaning towards this one

C) interesting but unrelated to the evolution of modern species

D) evidence that traits are acquired through use or disuse - I know it can't be this one either

D. evidence that are acquired through use or disuse. Since it is believed that some parts of an organism developed through its need. For example a giraffe got its long neck becuase of reaching for a tree that could produce its food. Another example is the leg of a human which developed because of its need to walk. It was believed that the parts of the an organism did exist or did vanish depending if it was no longer used or it was necessarily needed to survive.