4. Consider the following observations: Two point charges [with the same magnimde} are labeled A and B. Charge A is due north of charge B. A proton is placed at rest at the mid- point on a line connecting the two point charges. The proton travels clue south. Which one of the following statements correctly indicates the signs ofthe two charges? a} Charge A is positive and charge B is negative. til Charge A is positive and charge B is positive. c] Charge A is negative and charge B is positive. dl Charge A is negative and charge B is negative