A metal ball is connected to the ground with a wire via a switch. The switch is initially closed (i.e. the ball is connected to ground) while a charge +Q is brought close to the ball (but not touching). While the charge is near the ball, the switch is opened and then the charge is taken away. The charge on the ball is now,
(a) zero.
(b) positive.
(c) negative.
(d) unchanged from its initial charge.