A figure skater is spinning slowly with arms outstretched. She brings her arms i

A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her angular speed increases dramatically. The speed increase is a demonstration of
A) conservation of energy: her moment of inertia is decreased, and so her angular speed must increase to conserve energy.
B) conservation of angular momentum: her moment of inertia is decreased, and so her angular speed must increase to conserve angular momentum.
C) Newton's second law for rotational motion: she exerts a torque and so her angular speed increases.
D) This has nothing to do with mechanics, it is simply a result of her natural ability to perform.