A pendulum is made from an aluminum rod with a mass attached to its free end. If the pendulum is cooled,

(a) Does the pendulum's period increase, decrease, or stay the same

(b) Choose the best explanation from among the following:

I. The period of a pendulum depends only on its length and the acceleration of gravity. It is independent of mass and temperature.

II. Cooling makes everything move more slowly and hence the period of the pendulum increases.

III. Cooling shortens the aluminum rod, which decreases the period of the pendulum.