D because it makes more sense
friction is a force that opposes motion and significantly slows the cars as they move on the track. While it is easy to believe that friction is bad for the ride, it is one of the forces engineers consider in ensuring passengers have a safe ride.
Sugar is a component of carbohydrates, but it should be noted that this is a slightly misleading question, since sugar itself is actually a carbohydrate.
Paleontology....Would be your answer...
