A. a negative charge
Explanation:
The electrostatic force acts between two charged objects. Its direction depends on the sign of the charges: the force is repulsive between two like charges, while it is attractive between two opposite charges. This means that two positive charges or two negative charges repel each other, while a positive and a negative charge attract each other. Therefore, the correct answer must be A. a negative charge, because a positive charge will attract a negative charge.
