In the diagram, rod R hangs from an insulating thread. When the positively charged rod Q is moved near rod R, rod R moves away from rod Q. What conclusion can be drawn from this observation?
- ARod R is charged, but it is not possible to identify the sign of the charge.
- BRod R must be positively charged.
- CRod R must be negatively charged.
- DRod R is uncharged.