16. The potential difference across the terminals of a battery is V1when there is a current of I1 in the battery from the negative to the positive terminal. When the current is Iz in the reverse direction, the potential difference becomes V.. (Note that V1, V2, I1 and I2 are all defined as positive values)Which statement is not correct for this system? (A) V1 = V2； (B) The internal resistance of the battery is (V2 - V1)/( I1 + I2)； (C) The enf of the battery is ( I1V2 + I2V1 )/(I1 + I2)； (D) All； (E) None.