Question: In an experiment studying phototropism, students grew bean plants in labeled cardboard milk cartons. Afterward, the plants and soil were properly discarded. Which instruction line BEST conserves the remaining resources?

  Options: 
 A. recycle the markers, reuse the milk cartons
 B. reuse the markers, discard the milk cartons
 C. discard the markers, reuse the milk cartons
 D. reuse the markers, recycle the milk cartons
Answer: D