The can be found elsewhere and as follows:
A. of magnetic effects.
B. the ball tries to pull the rod’s electrons over to it.
C. the rod polarizes the metal.
D. the rod and the ball have opposite charges.
I believe the correct answer is option C. If a negatively charged rod is held near a neutral metal ball, the ball is attracted to the rod. this happens because the rod polarizes the metal. Hope this answers the question.