Answer: Potential; Kinetic
Explanation:
''...During this process, potential energy has been changed into kinetic energy.''
Potential energy is the energy that a stationery object has because it is stored within the object. In this case the object is the book.
When an object begins to move, it gains kinetic energy which is converted from its potential energy. As the book falls to the floor in this scenario, it gained kinetic energy as its potential energy was converted to enable it move.