The correct statement that describes the energy transformation as the roller coaster moves from point A and stops at point B is:
Potential changes to kinetic, then some kinetic changes to potential.
As the roller coaster descends from a higher point (A), its potential energy is converted into kinetic energy, causing it to accelerate. As the roller coaster climbs back up or slows down at point B, some of that kinetic energy is converted back into potential energy.