The pedigree of Seattle Slew, a racehorse considered by some to be one of the fastest horses that ever lived, includes very fast horses on both his mother's side and his father's side. Seattle Slew most likely was a result of

selective breeding

Explanation:

The Seattle Slew was the most famous horse. It was a dark bay horse having a small white patch of hair to his left rear hoof. It was the champion racehorse.

The Seattle Slew was considered to be the fastest horse on the race course in the world. It won many championship. The pedigree of the Seattle Slew consists of the fast horses from both the mother's side as well as the father's side. He was most likely a result of a selective breeding that made him the fastest horse that ever lived, as believed by some people.

it's c. (to reduce the greenhouse effect/carbon gasses)