The answer is A, a mountain building.
The two faces of the book represent the tectonic plates
As he presses them towards each other he is modeling a convergent boundary, and mountains are an affect of convergent plates.
The answer is Abduction. In medicine and biomechanics, movements of limbs and other body parts toward or away from the center line of the body are termed as adduction and abduction respectively. Adduction is the movement of a body part toward the body's midline. Abduction is the movement away from the mid line. For example, abduction of the shoulder raises the arms out to the sides of the body.