Hi there!
[tex]\boxed{\text{Her angular velocity decreases.}}[/tex]
Recall the conservation of angular momentum:
[tex]L_i = L_f\\\\I_iw_i = I_fw_f[/tex]
When this person extends her arms, her moment of inertia increases.
According to the conservation of angular momentum, if the moment of inertia increases, the angular velocity must DECREASE.
