Why don't the electrons stay on the rubber belt when they reach the upper comb? a The upper comb has no excess electrons and the excess electrons in the rubber belt get transferred to the comb by contact b The upper comb has no excess electrons and the excess electrons in the rubber belt get transferred to the comb by conduction The upper comb has excess electrons and the excess electrons in the rubber belt get transferred to the comb by conduction. d The upper comb has excess electrons and the excess electrons in the rubber belt get transferred to the comb by contact.