A teacher cut an apple into three wedges of the same size. She dipped one wedge in lemon juice, dipped another in water, and left one alone. Then she left the wedges on a paper towel on her desk. After 1 hour, only the wedge that had been dipped in lemon juice was still yellow. The other two wedges had turned brown. What is the responding variable in this experiment? O A. The color of the apple wedges after 1 hour B. The size of the apple wedges C. The lemon juice applied to one of the apple wedges D. The liquid the apple wedges were dipped in