Answer:
a. When she pulls in her arms, the work she performs on them turns into increased rotational kinetic energy
Explanation:
When she pulls her arms , the moment of inertia decreases due to which the angular velocity increases to conserve angular momentum . Due to increase in angular velocity , her rotational kinetic energy increases . The source of this additional energy is work done by her against the centrifugal force . The work done by her is converted into rotational kinetic energy.