6. A type of cell called the lymphocytes makes proteins that are exported from the cell. You can track the path of these proteins by using pulse-chase experiment with radioisotope-labeled proteins to demonstrate the classic secretory pathway in cells. Which of the following might be the classic secretory pathway for those polypeptides to be sorted out? (A) rough ER -- lysosome --- plasma membrane (B) smooth ER -- Golgi --- plasma membrane (C) nucleus -- rough ER -- Golgi --- plasma membrane (D) rough ER -- Golgi --- plasma membrane (E) rough ER --- mitochondria -- Golgi --- plasma membrane