When a plastic rod is rubbed against a silk cloth and brought near a metal plate, it is attracted to the metal plate. Which of the following correctly shows charges on both the plastic rod and metal plate?
a. Negatively charged plastic rod faces positively charged side of the metal plate.
b. Negatively charged plastic rod faces negatively charged side of the metal plate.
c. Negatively charged plastic rod faces uncharged side of the metal plate.
d. Negatively charged plastic rod faces uncharged side of the metal plate.