The pirouette effect:

The pirouette effect explains that the angular velocity of a body changes, if part of its mass changes its position relatively to the axis of rotation of the body. Therefore it is important, how great the distance between the mass and the axis of rotation is.

How can the velocity of a rotating body be decreased ?

a) By distributing mass inwards and thus closer to the axis of rotation.

b) By distributing mass outwards and thus farther away from the axis of rotation.