A neutral conducting ball is suspended by an insulating thread. The following sequence is carried out:
1. A positively charged rod is brought close to, but does not touch, the ball and is held stationary.
2. While the rod remains in place, the ball is momentarily connected to ground with a conductor.
3. The grounding connection is removed.
4. The charged rod is finally pulled far away.
Which statement best describes the net charge on the ball after step 4 and the primary reason for that result?
a) The ball is positively charged because electrons were pushed down into Earth while the positive rod was nearby.
b) The ball is negatively charged because protons were repelled into Earth during the grounding step.
c) The ball is negatively charged because electrons were drawn up from Earth while the positive rod was nearby.
d) The ball is neutral because any induced charges returned to their original positions once the rod was removed.