According to “roller coaster physics,” the lift hill is “…essential to the remaining trip for the cars on the track.”
which of the following sentences from the passage best supports this idea?
a
the cars of the train are pulled up the first steep hill, which builds potential energy for the rest of the ride.

b
once the train cars crest the lift hill, gravity pulls the front of the train down the tracks.

c
the higher the hill is, the greater the distance that the train can run.

d
as the car leaves the lift hill, the train begins to fall down the track.