Answer:
Rabbit fur
Step-by-step explanation:
When you rub the rabbit fur on the rubber rod it will become negatively charged because of it's placement on the electrostatic series. If you were to rub it agains say the cotton there would be less electrons transfered and though the rubber rod would still be negative and the cotton positive it would be less negative and positive with means less electrons moving. This is due to the fact that the rabbit fur is more likely to loss electrons and the rubber rod to gain electrons because both objects start negative.