A figure skater has a moment of inertia of 4.0 kg.m² with her arms outstretched. If she begins spin at 3.0 rad/s with her arms outstretched and then brings her arms in tight to her body, her of spin increases to 7.0 rad/s in 2.5 seconds. As the skater brings her arms in tight to her body, what torque is applied to increase her spin.

1) 2.7 N.m

2) 4.0 N.m

3) 5.3 N.m

4) no torque is applied to increase her spin