A system consisting of a positively-charged particle and an electric field a. loses potential difference and kinetic energy when the charged particle moves in the direction of the field. b. loses electric potential energy when the charged particle moves in the direction of the field. c. loses kinetic energy when the charged particle moves in the direction of the field. d. gains electric potential energy when the charged particle moves in the direction of the field. e. gains potential difference and electric potential energy when the charged particle moves in the direction of the field.