You Perform an Experiment in Which You Take 16 Pots

You perform an experiment in which you take 16 pots of strawberry plants and give half of them 1 gram of ammonium nitrate per liter of water and the other half just get water. Each group is then split in half again, and exposed to either 8 or 16 hours of light each day. You monitor the height of the plants for four weeks. You observe that increasing ammonium nitrate and light both increase plant height.
-Which of the following is a (are) dependent variable(s) in this experiment?

A) the height of the plants and amount of light
B) the amount of ammonium nitrate and light
C) the amount of light
D) the height of the plants
E) the amount of ammonium nitrate